Chemistry College

## Answers

**Answer 1**

The question requires us to provide the IUPAC name for the structure given.

To determine the IUPAC name of an organic compound, first we need to analyze a few characteristics of the structure, for example: if it is linear or not, if it has ramifications, if it presents double or triple bonds, if it contains hom*ogeneous, if it contains any "special groups" (such as ketone and esthers) etc.

For the structure presented, we can see that it is a linear chain that contains ramifications and only presents simple bonds, thus it is an alkane (the final part of its name must be -ane).

Next, we must find the main chain, which in this case corresponds to the longest sequence of carbons possible. We can see that the structure presented has 9 carbons on its main chain, as highlighted in orange in the image below:

Thus, the name of this compound (still not considering the ramifications) must be "nonane" (9 carbons on the main chain of an alkane).

Next, we must take the ramifications into consideration: there are 3 methyl structures (-CH3) attatched to the main chain (highlighted in blue in the following image):

We must number their position in a way that we achieve the smallest numbers possible. To do that, we can start numbering the main chain from the right to the left, as shown below:

(This way, the sum of the radical positions would be 2+5+6 = 13, instead of 4+5+8=17 that we would obtain numbering the chain from left to right)

Therefore, the methyl groups are bonded to the carbons 2, 5 and 6 from the main chain.

Putting all these information together (alkane with 9 carbons and three methyl groups in the positions 2,5 and 6), we'll have **the name ****2,5,6-trimethylnonane**** for the structure given**.

## Related Questions

A solution has a hydroxide ion concentration of 0.001 M. What is the pH of the solution?Group of answer choices37111314

### Answers

pOH = - log10[OH-]

pOH= −log10(1×10−3)

pOH = 3

we know that :

pH+ pOH=14

pH =14 - pOH

therefore pH=14−3

= 11

The pH of the solution is **11**

Not sure on how to do this using the table method and how to cancel units.

### Answers

This is a stoichiometry problem, where we have an initial amount of reactant and we need to find out how much of the product will we end up with, in order to do that we need to:

1. Set up the properly balanced equation, which the question already provided us

2 H2 + O2 -> 2 H2O

2. See how many moles of reactant there are in the given amount of grams, which we don't have to do since the question already gave us the number of moles of Hydrogen, 6.0 moles

3. Check the molar ratio between the two compounds, which will be 2:2, the same amount of moles of H2 is needed to produce the same amount of moles of H2O, therefore if we have 6 moles of H2, we will also have 6 moles of H2O

4. Calculate how many grams will be equal to the number of moles that we found out, we will do that by calculating the number of moles with the molar mass, 18g/mol

18g = 1 mol

x grams = 6 moles

x = 108 grams of H2O will be produced

For the purpose of the table, everything I write left will be on the top side, everything I write right will be on the bottom

6 moles of H2

2 moles of H2O/2 moles of H2 (H2 will cancel out)

18 grams of H2O/1 mol of H2O (mol will cancel)

108 grams of H2O will be the final answer

What is the skeletal equation? I have the word equation just need the skeletal for question number e

### Answers

In word equation, you need to write the name of each compound, reactants and products. In this case, it is:

Word:

Aluminum + Copper (II) Chloride --> Copper + Aluminum

chloride

The skeleton equation you must put the formulas of the compounds written in word equation.

Skeleton:

Al(s) + CuCl2(aq) --> Cu(s) + AlCl3(aq)

**Answer:**

**Word:**

**Aluminum + Copper (II) Chloride --> Copper + Aluminum **

**chloride**

**Skeleton:**

**Al(s) + CuCl2(aq) --> Cu(s) + AlCl3(aq)**

Show how by calculation how you will prepare 1.0x10-2 M NaOH from 0.1 M NaoHstock solution

### Answers

To prepare 1.0x10^-2M NaOH from 0.1M NaOH stock solution, you have to take a volume of the stock solution and dilute it using 9 times that volume of water. We conclude it from the equation for dilutions:

[tex]\begin{gathered} V1C1=V2C2 \\ 0.1V1=0.01V2 \\ \frac{0.1}{0.01}V1=V2 \\ 10V1=V2 \\ V1=\frac{1}{10}V2 \end{gathered}[/tex]

It means that to prepare the 1.0x10^-2 solution, dilute 1 mL (for instance) of stock solution in 9mL of water.

An ion in the 17th column of the Periodic table has 53 protons how many electrons does it have?

### Answers

The question requires us to identify how many electrons in an ion which contains 53 protons and it is located in the 17th column of the periodic table.

Atoms are made of three basic particles: protons, electrons and neutrons. The nucleus of the atom contains the protons (positively charged) and the neutrons (no charge), while the electrons (negatively charged) are located in the outermost regions of the atom.

We can determine the number o protons, electrons and neutrons in an atom with a set of simple rules:

- The number of protons in the nucleus of the atom is equal to the atomic number (Z);

- The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus and the number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z);

- The number of electrons in a neutral atom is equal to the number of protons.

Knowing that the number of electrons in a *neutral atom* is the same as the number of protons, we can say that the *neutral atom* mentioned by the question contains 53 electrons.

Since the question mentions it is an ion, we need to consider its group in the periodic table to identify the charge of this ion and, therefore, identify the number of electrons it contains.

Elements in the 17th column of the periodic table, such as fluorine (F), chlorine (Cl) and bromine (Br), tend to receive one electron and form anions with charge -1.

Therefore, **the ion mentioned by the question would present charge -1 and ****54 electrons****, since it receives one additional electron.**

If 214.0 mL of a gas at 616.20 mmHg and 11.9°C is heated in a flexible container, and the final pressure ismeasured at 261.90 mmHg with an expanded volume of 512.0 mL, what is the final temperature of this gasin degrees Celsius?(Show all work)A) 333B) 16.7C) 290D) 14.0

### Answers

**Answer**

**B) 16.7**

The final temperature of this gas in degrees Celsius = **16.7 **°**C**

**Explanation**

Given:

Initial volume, V₁ = 214.0 mL

Initial pressure, P₁ = 616.20 mmHg

Initial temperature, T₁ = 11.9 °C

Final pressure, P₂ = 261.90 mmHg

Final volume, V₂ = 512.0 mL

What to find:

The final temperature of this gas in degrees Celsius.

Step-by-step solution:

The first step is to convert the temperature to K.

**Conversion factor:**

0 °C = 0 + 273.15 K

∴ **T₁** = 11.9 °C = 11.9 + 273 K = **285.05 K**

The next step is to calculate the final temperature in K using the **combined gas equation.**

[tex]\begin{gathered} \frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2} \\ \\ \Rightarrow T_2=\frac{P_2V_2T_1}{P_1V_1}=\frac{261.90mmHg\times512mL\times285.05K}{616.20mmHg\times214mL}=289.86\text{ }K \end{gathered}[/tex]

The final step is to convert **289.86 K to **°**C.**

**Conversion factor:**

0 K - 273.15 = -273.15 °C

Therefore, 289.86 - 273.15 = 16.71 °C = **16.7 **°**C**

The final temperature of this gas in degrees Celsius is **16.7 **°**C**

the number of moles of solute in a bottle containing 225 mL of 0.220 mol/l sodium sulfide solution is?

### Answers

In order to find the answer for this question we will use the Molarity formula, which is:

M = n/v

where

M = molar concentration or molarity in mol/L

n = number of mols

v = volume in Liters

Now using the values given in the question we will have:

0.220 = n/0.225

n = 0.0495 moles of solute

How many moles are in 88.72 grams of EcoH306?Ec has a molar mass of 31.79 grams/mole.(Hint: You need to determine the molar mass of EcoH306 to solve this problem).

### Answers

We want to find the number of moles of EcoH306.

Given:

mass = 88.72 g

molar mass = 31.79 g/mol

The formula to use for this problem:

n = m/M

where n is the number of moles, m is the mass and M is the molar mass of EcoH306.

n = m/M

n = (88.72g)/(31.79g/mol)

**n = 2.791 mol**

LiOH(s) + CO2(g) —> LiHCO3(s)Determine the limiting reagent if you have 30.0 grams of both LiOH and CO2.

### Answers

ANSWER

The limiting reagent for the reaction is **CO2**

EXPLANATION

Given that;

*The mass of LiOH that reacted is 30.0 grams*

*The mass of of CO2 that reacted is 30.0 grams*

Follow the steps below to find the limiting reactant of the reaction.

Step 1; Find the mole of each reactant

[tex]\text{ mole = }\frac{\text{ mass}}{\text{ molar mass}}[/tex]

Recall, that the molar mass of LiOH and CO2 are **23.95 g/mo**l and **44.01 g/mol **respectively.

For LiOH

[tex]\begin{gathered} \text{ mole = }\frac{\text{ 30}}{\text{ 23.95}} \\ \text{ mole = 1.253 moles} \end{gathered}[/tex]

The number of moles of LiOH is 1.253 moles

For CO2

[tex]\begin{gathered} \text{ mole = }\frac{\text{ mass}}{\text{ molar mass}} \\ \text{ mole = }\frac{\text{ 30}}{\text{ 44.01}} \\ \text{ mole = 0.682 mol} \end{gathered}[/tex]

The mole of CO2 in the reaction is 0.682 mol

In chemical reaction, the limiting reagent of the reaction always has the least number of moles.

Hence, the limiting reagent for this reaction is **CO2**

Which charge does iron (Fe) have in iron sulfate (FeSO4)?A) +2B) -1C) -2D)+1

### Answers

Answer:

+2. **Option A** is correct.

Explanations:

Given the compound FeSO₄, we are to get the** charge on Iron(Fe)**. From the given compound;

• The o,xidation state ,of sulfur (S) is +6

,

• Oxidation state of oxygen is -2(4) = -8

Let the **oxidation state** of **iron (Fe) be "x"**

Taking th**e sum of the oxidation state** and equate to zero to get the value of "x"

[tex]x+6+(-8)=0[/tex]

**Simplify the result**

[tex]\begin{gathered} x+6-8=0 \\ x-2=0 \\ x-2+2=0+2 \\ x=+2 \end{gathered}[/tex]

This shows that the **charge on iron** in** FeSO4 is +2**

A 16.9 g sample of CaSO4 is found to contain 4.98 g of Ca and 7.94 g of O. Find the mass of sulfur in a sample of CaSO4 with a mass of 49.5 g.

### Answers

The first step to solve this problem is to find the number of moles of CaSO₄ that we have in a sample of 49.5 g of it. To do that we will find the molar mass of CaSO₄. We have to look for the atomic mass of each element that is present in the molecule.

Ca: 40.08 amu

S: 32.07 amu

O: 16.00 amu

Using that information we can find the molar mass of CaSO₄.

molar mass of CaSO₄ = 40.08 + 32.07 + 4 * 16.00

**molar mass of CaSO₄ = 136.15 g/mol**

Using the molar mass we can find the number of moles of CaSO₄ that we have in a sample of 49.5 g of it.

number of moles of CaSO₄ = 49.5 g / (136.15 g/mol)

**number of moles of CaSO₄ = 0.360 moles**

In one mol of molecules of CaSO₄ we have 1 mol of atoms of S (since there is 1 atom of S in one molecule of CaSO₄). Let's use that relationship to find the number of moles of S atoms that there are in 0.360 moles of CaSO₄.

number of moles of S = 0.360 moles of CaSO₄ * 1 mol of S/ (1 mol of CaSO₄)

**number of moles of S = 0.360 moles **

Finally we can find the mass of S using the molar mass of O.

molar mass of S = 32.07 g/mol

mass of S = 0.360 moles * 32.07 g/mol

**mass of S = 11.55 g**

**Answer: the mass of sulfur in a 49.5 g sample of CaSO₄ is 11.55 g**

Water with a H3O+ concentration of 1 x 10^-7 M has a pH of

### Answers

**Answer**:

The water has a pH of 7.

**Explanation**:

To calculate the pH, we can use the pH formula and replace the concentration of H3O+:

[tex]\begin{gathered} pH=-log{}{}[H_3O^+] \\ pH=-log(1*10^{-7}) \\ pH=7 \end{gathered}[/tex]

So,** **the** pH is 7**.

Calculate the mass percent of a NaCl solution in which 160 g of NaCl is dissolved in 3.13 L of water at 25 ∘C (density = 0.997 g/mL).Express your answer numerically.

### Answers

The formula of mass percent is the following:

[tex]\text{mass percent=}\frac{mass\text{ of solute}}{mass\text{ of solution}}[/tex]

where mass of solute correspond to the mass of NaCl and mass of solution correspond to the sum of NaCl and water mass.

We need to find the mass of water using its volume and density:

[tex]\text{mass of water=}\frac{\text{density}}{\text{volume}}=\frac{0.997\text{ g/mL}}{3130\text{ mL}}=0.997\text{ g water}[/tex]

And we replace it in the first formula like this:

[tex]\text{mass percent=}\frac{160}{160+0.997}=0.9938[/tex]

We obtain the percent multiplying the result by 100, so the answer is **99.38%**

Not a timed or graded assignment. Please refer to requirements circled in red, quick answer = amazing review :)

### Answers

For this problem, we have to use Avogadro's number which is 6.022 x 10^(23) /mol. This number is telling us that there are 6.022 x 10^(23) atoms in 1 mole of a certain compound/element. The conversion would be:

[tex]0.30molesSO_2\cdot\frac{6.022\cdot10^{23}atoms}{1\text{ mol}}=1.8\cdot10^{23}atoms.[/tex]

The answer is that **there are**** 1.8 x 10 ^(23) atoms of SO2 ****in 0.30 moles.**

Can somebody help me solve this ? I dont get how to do it

### Answers

**Answer**:

The mass of water is 25.9g.

**Explanation**:

**1st)** It is necessary to use the Heat formula. Knowing that the piece of aluminum releases heat and the water absorbs heat, the equation is a sum of both heats euqal to zero:

[tex]Q_{Al}+Q_{water}=0[/tex]

**2nd) **The information given in the exercise is:

• Piece of aluminum:

- Mass (mAl)=55.0g

- Heat capacity (cAl)=0.902J/°C*g

- Initial Temperature (TiAl)= 72.4°C

- Final Temperature (TfAl)= 44.9°C

• Water:

- Mass (mwater)= this is what we have to calculate.

- Heat capacity (cwater)= 4.18J/°C*g

- Initial Temperature (Tiwater)= 32.3°C

- Final Temperature (Tfwater)= 44.9°C

**3rd)** It is necessary to replace the values in the formula to calculate the mass of the aluminum piece:

[tex]\begin{gathered} -Q_{Al}=Q_{water} \\ -\lbrack m_{Al}*c_{Al}*(T_{fAl}-T_{iAl})\rbrack=m_{water}*c_{water}*\left(T_{fwater}-T_{iwater}\right) \\ -\lbrack55.0g*0.902\frac{J}{\degree C*g}*(44.9°C-72.4°C)\rbrack=m_{water}*4.18\frac{J}{\operatorname{\degree}C*g}*(44.9°C-32.3°C) \\ -\lbrack-1364.28J\rbrack=m_{water}*52.67\frac{J}{\operatorname{\degree}C} \\ \frac{1364.28J}{52.67\frac{J}{g}}=m_{water} \\ m_{water}=25.9g \\ \end{gathered}[/tex]

Resolution number 2 (image):

Finally, **the mass of water is 25.9g**.

31.The process in which solutions of an acid and a base react to form water and a salt is called...Select one:a. dissociation.b. ionization.c. neutralization.d. synthesis.

### Answers

**Answer:**

[tex]C\text{ : Neutralization}[/tex]

**Explanation:**

Here, we want to select the process in which a solution of an acid react with a base to form salt and water

This process is called neutralization

It is the process by which solutions of an acid or a base react to form salt and water

2) A gas is held in a sealed glass container. The initial pressure and temperature are 0.150 atm and 72 ° C. If the final temperature is 157 ° C, what is the final pressure (in atmospheres)?

### Answers

**Answer**:

The final pressure is 0.3297atm.

**Explanation**:

**1st)** The given information from the exercise is:

- Initial pressure (P1): 0.150atm

- Initial temperature (T1): 72°C

- Final temperature (T2): 157°C

**2nd) **To calculate the final pressure, we can use the Gay-Lussac's formula, by replacing the values:

[tex]\begin{gathered} \frac{P_1}{T_1}=\frac{P_2}{T_2} \\ \frac{0.150atm}{72°C}=\frac{P_2}{157°C} \\ 0.0021\frac{atm}{°C}=\frac{P_2}{157°C} \\ 0.0021\frac{atm}{°C}*157°C=P_2 \\ 0.3297atm=P_2 \end{gathered}[/tex]

So, **the final pressure is 0.3297atm**.

Propylene has a molar mass of 42 grams and is composed of 85.7% carbon and 14.3% hydrogen, what is its molecular formula?

### Answers

Answer:

**C3H6**

Explanations:

**Given the following **parameters

%carbon = 85.7%

%Hydrogen = 14.3%

**Convert percentage to mass**

Mass of carbon = 85.7grams

Mass of Hydrogen = 14.3 grams

Convert **mass to moles**

Moles of Carbon = 85.7/12 = 7.142moles

Moles of Hydrogen = 14.3/1 = 14.3 moles

Divide by the **lowest ratio**

For Carbon: 7.142/7.142 = 1

For Hydrogen: 14.3/7.142 = 2.002

Determine the **empirical formula**

Empirical formula = CH2

Determine the **molecular formula**

(Empirical formula)n = molar mass of Propylene

(CH2)n = 42

(12 + 2(1))n = 42

14n = 42

n = 42/14

n = 3

Molecular formula = (CH2)3 = C3H6

Therefore the **molecular formula** of propylene is** C3H6**

A sample of neon initially has a volume of 2.00 L at 16 ∘C. What final temperature, in degrees Celsius, is needed to change the volume of the gas to each of the following, if pressure and amount of gas do not change?Part A) 6.00 L

### Answers

To do this problem we will use Charles' law. Charles law states that the volume of a given mass of gas varies directly with the absolute temperature of a gas when pressure is kept constant.

Charles law:

[tex]\begin{gathered} \frac{V_1}{T_1}=\frac{V_2}{T_2} \\ V_1:inital\text{ }volume\text{ }(L)=2.00L \\ T_1:initial\text{ }temperature\text{ }(K)=16\degree C \\ V_2:final\text{ }volume\text{ }(L)=6.00L \\ T_2:final\text{ }temperature\text{ }(K)=x \end{gathered}[/tex]

By substituting what is given into the formula to determine the unknown we have:

[tex]\begin{gathered} \frac{2.00L}{16\degree C}=\frac{6.00L}{x} \\ \\ x=(6.00L\times16\degree C)\div2.00L \\ x=48\degree C \end{gathered}[/tex]

**Answer: The final temperature of the gas is 48 degrees celcius. **

What is the smallest particle in the list below?A piece of dustA cell of E. coliAn atomA skin cell

### Answers

ANSWER

**The smallest particle is an atom**

**EXPLANATION**

**An atom** is defined as the smallest indivisible particle of a substance that can take part in a chemical reaction and still retain it properties

An atom make up everything in the universe

Hence, **the smallest particle is an atom**

Based on the balanced chemical reaction, if you desired to produce 2.50g of NaCI in this reaction, how many grams of Na2CO3 would need to be used. Na2CO3 105.99NaCI 2.50g58.44g NaCl

### Answers

Na2CO3 (s) + 2 HCl (aq) ---> 2 NaCl (aq) + H2O (l) + CO2 (g)

First you must balance the reaction:

Number of atoms on the left = Number of atoms on the right

Na2CO3 (s) + 2 HCl (aq) ---> 2 NaCl (aq) + H2O (l) + CO2 (g)

x 2.50 g

x is the unknown we are looking for. It is the mass of the Na2CO3 we need to use to produce 2.50 g of NaCl.

We know from the reaction that:

1 mol of Na2CO3 = 105.99 g

1 mol of NaCl = 58.44 g

The next is:

105.99 g Na2CO3 ----------------- 2 x 58.44 g NaCl

x ------------------ 2.50 g NaCl

[tex]x\text{ = }\frac{2.50\text{ g NaCl x 105.99 g Na2CO3}}{2\text{ x 58.44 g NaCl}}=\text{ 1.81 g Na}2CO3[/tex]

f

How many kJ are produced when 50.0 g of oxygen reacts with excess H2(g) in the following reaction?2H2(g) + O2(g) → 2H2011) + 572 kJYour Answer:

### Answers

we are given the equation

2H₂(g) + O₂(g) → 2H₂011) + 572 kJ

and we are required to find the amount of KJ produced when 50 g of oxygen are reacted with excess hydrogen

solution

50 grams of oxygen has :

Mols = m/M

= 50/16.00

= **3.125 mols **

from the balance equation we see that when 1 mol of oxygen reacts with 2 mols of Hydrogen +572KJ of energy are produces. therefore when 3.125 mols of oxygen are reacted we get :

3.125 x 572

= 1787 KJ

therefore **1787KJ** of energy will be produced

Calculate the number of moles of Cl atoms in 1.81×1024 formula units of magnesium chloride, MgCl2.Express your answer numerically in moles.

### Answers

1) Convert the number of molecules into the number of Cl atoms

[tex]Cl\text{ atoms=1.81}\cdot10^{24}moleculesofMgCl_2\cdot\frac{2\text{ atoms of Cl}}{1moleculeofMgCl_2}=3.62\cdot10^{24}\text{ Cl atoms}[/tex]

There are 3.62*10^24 Cl atoms in 1.81×10^24 of MgCl2.

2) Convert the number of Cl atoms into moles of Cl.

[tex]\text{mol Cl=3.62}\cdot10^{24}\text{ Cl atoms}\cdot\frac{1\text{ mol Cl}}{6.022\cdot10^{23}\text{ Cl atoms}}=6.011\text{ mol Cl.}[/tex]

**There is 6.011 mol Cl in 1.81×10^24 of MgCl2.**

Need help feeling in the blink for this practice sheet

### Answers

**Answer**

**Procedure**

Data

Use the calibration curve to determine the value of the diluted unknowns as indicated in the image below.

At an absorbance value of 0.5, the concentration is 0.036

At an absorbance value of 0.750, the concentration is 0.056

At an absorbance value of 1, the concentration is 0.074

The value of 1.25 is outside the graph but by creating an equation we will have

y=13.146 +0.0226

where we can replace y as the absorbance 1.25 and solve for X (concentration) we get a value of 0.0933 M

At an absorbance value of 1.25 , the concentration is 0.0933

To solve the concentration we can use the formula provided now that we know the diluted concentration.

After applying the formula and calculating the average and standard deviation the complete table looks as follows

Which comes first melting or freezing point or condensing or boiling point?

### Answers

**Answer**

**Letter A = FreeziExplanation**

The state of the matter depends upon the temperature. Each state (solid, liquid, and gas) has its own unique set of physical properties.

Common changes of the state include melting (solid to liquid), freezing (liquid to solid), sublimation (solid to gas), deposition (gas to solid), condensation (gas to liquid), and vaporization (liquid to gas).

From the given graph, A indicates a change from liquid to solid, hence, the **letter A is the Freezing point.**

What is the initial volume, in milliliters, needed to prepare each of the following diluted solutions?350. mL of 0.80 %(m/v) NaCl from 4.0 % (m/v) NaCl

### Answers

ANSWER

The initial volume of the solution is **70mL**

**EXPLANATION**

Given that;

The initial concentration of the solution is 4.0%

The final concentration of the solution is 0.80%

Th e final volume of the solution of is 350mL

Follow the steps below to find the initial volume of the solution.

Step 1; Apply the dilution formula

[tex]\begin{gathered} \text{ C1 V1 = C2 V2} \\ \end{gathered}[/tex][tex]\begin{gathered} \text{ }\frac{\text{ 4}}{\text{ 100}}\text{ }\times\text{ V1 = }\frac{\text{ 0.80}}{\text{ 100}}\times\text{ 350} \\ \text{ 0.04 }\times\text{ V1 = 0.008 }\times\text{ 350} \\ \text{ 0.04V1 = 2.8} \\ \text{ Divide both sides by 0.04} \\ \text{ }\frac{\text{ 0.04V1}}{\text{ 0.04}}\text{ = }\frac{\text{ 2.8}}{\text{ 0.04}} \\ \text{ V1 = 70mL} \end{gathered}[/tex]

Therefore, the initial volume of the solution is **70mL**

please explain moles concept

### Answers

**Answer:**

A mole is the amount (10) of material containing 6.02214 × 10 raised to the power of 23 particles.

When the following chemical equation is correctly balanced, what will be the coefficient for N2H4? ___________N2H4 + ___________N2O4 ----------> ________N2 + _______H2OGroup of answer choices12345

### Answers

**ANSWER**

[tex]\text{ The number of moles of N}_2H_4\text{ is 2}[/tex]

**EXPLANATION**

Given that:

[tex]\text{ N}_2H_4\text{ }+\text{ N}_2O_4\text{ }\rightarrow\text{ N}_2\text{ }+\text{ H}_2O[/tex]

To balance the above equation, apply the law of conservation of mass

**The law of conservation of mass** states that matter can neither be created nor destroyed but can be tranformed from on point to another.

The above law implies that the total number of atoms on the reactant side must be equal to the total number of atoms on the products side

**On the reactant side**, we have,

4 atoms of nitrogen

4 atoms of hydrogen

4 atoms of oxygen

**On the product sides**

2 atoms of hydrogen

2 atoms of nitrogen

1 atom of oxygen

To balance the equation, we have,

2 moles of N2H4

1 mole of N2O4

3 moles of N2

4 moles of water

[tex]\text{ 2N}_2H_4\text{ }+N_2O_4\text{ }\rightarrow\text{ 3N}_2\text{ }+\text{ 4H}_2O[/tex]

In the new equation above, we have the following

**on the reactants side**

6 atoms of nitrogen

8 atoms of hydrogen

4 atoms of oxygen

**on the products side**

6 atoms of nitrogen

8 atoms of hydrogen

4 atoms of oxygen

Therefore, the number of moles of N2H4 is** 2**

Choose the option that best completes the sentence.__ is the process of matter changing from a solid to a liquid, while__ is the process of matter changing from gas to liquid

### Answers

**Explanation:**

Melting is the process of matter changing from a solid to a liquid.

Condensation is the process of matter changing from gas to liquid.

**Answer:**** Melting, condensation.**

What is the molar mass of an unknown gas with a density of 2.65 g/L at 3.00 atm and 45.0 °C?

### Answers

In order to solve this question, we will need to use two very common formulas, the first it will be the Ideal gas Law, but with a few changes, and the second it will be the density formula:

PV = nRT, this is the Ideal gas formula, and we have:

P = 3.00 atm

T = 45°C, but we need it in Kelvin, 318 K

R = 0.082, this is the gas constant

d = m/V, this is the density formula, and we have:

d = 2.65 g/L

Now let's make a few changes on the ideal gas formula, first switching n (number of moles) for m/MM (mass/molar mass)

PV = m/MM * RT

P*MM/RT = m/V, now we have m/V, which is the same as density, now we can use the values

3 * MM/0.082 * 318 = 2.65

3 * MM/26.076 = 2.65

3MM = 69.10

MM = 23.03g/mol, this is the final molar mass