Question 1

Which one of the following compounds contains the smallest percent oxygen by mass?

Accepted Answer

The percent oxygen by mass in a compound can be calculated by dividing the mass of oxygen in the compound by the total mass of the compound, then multiplying by 100. For compound D (CS₂O), the mass of oxygen is significantly lower relative to the total mass of the compound compared to the other options, which contain more oxygen atoms or heavier elements that do not contribute to the oxygen percentage as significantly.

Question 2

Which one of the following contains 52% carbon by mass?

Accepted Answer

CH3OCH3 contains 52% carbon by mass.

Question 3

When silver nitrate reacts with barium chloride,silver chloride and barium nitrate are formed.How many grams of silver chloride are formed when 10.8 g of silver nitrate reacts with 15.0 g of barium chloride?

Accepted Answer

1) Write the balanced chemical equation:
AgNO3 + BaCl2 → AgCl + Ba(NO3)2
2) Determine the limiting reactant:
AgNO3 → molar mass = 169.87 g/mol 
10.8 g ÷ 169.87 g/mol = 0.0636 mol
BaCl2 → molar mass = 208.23 g/mol
15.0 g ÷ 208.23 g/mol = 0.0721 mol
Thus, AgNO3 is the limiting reactant because it produces less moles of product.
3) Calculate the mass of AgCl produced:
Molar ratio of AgNO3 to AgCl is 1:1
0.0636 mol AgNO3 × 1 mol AgCl × 143.32 g/mol AgCl = 9.11 g AgCl
Therefore, the answer is A) 9.11 g of silver chloride are formed.

Question 4

Which one of the following is not an empirical formula?

Accepted Answer

An empirical formula represents the simplest whole-number ratio of elements in a compound. C₂H₂O₄ can be simplified to CHO₂, so it is not an empirical formula.

Question 5

What is the empirical formula of a substance that contains 12.0 g of C,2.00 g of H,and 5.33 g of O?

Accepted Answer

The moles of each element are calculated as follows: C: 12.0 g / 12.01 g/mol = 1 mol, H: 2.00 g / 1.008 g/mol = 1.98 mol, O: 5.33 g / 16.00 g/mol = 0.333 mol. The simplest ratio is approximately 3:6:1, giving the empirical formula C₃H₆O.

Question 6

Balance the chemical equation given below,and calculate the volume of nitrogen monoxide gas produced when 8.00 g of ammonia is reacted with 9.00 g of oxygen at 25°C? The density of nitrogen monoxide at 25°C is 1.23 g/L. ________ NH₃(g)+ ________ O₂(g)→ ________ NO(g)+ ________ H₂O(l)

Accepted Answer

First, balance the chemical equation: 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(l). Then, calculate moles of NH3 (8.00 g / 17.03 g/mol = 0.47 mol) and O2 (9.00 g / 32.00 g/mol = 0.28 mol). The limiting reactant is O2, which produces 0.28 mol * (4 mol NO / 5 mol O2) = 0.224 mol NO. The volume of NO at 25°C is 0.224 mol * 24.45 L/mol (using ideal gas law at room temperature) = 5.48 L, which rounds to 5.49 L when considering the density of NO is 1.23 g/L for conversion if needed.

Question 7

Consider the following balanced reaction. 4A + 2B → 2C + D
8.0 moles of A and 30.moles of B react to form 2.5 moles of C.What is the percent yield of this reaction?

Accepted Answer

First, we need to determine the limiting reactant. Using the stoichiometry of the reaction, we can see that 4 moles of A react with 2 moles of B to form 2 moles of C. Therefore, we can determine that 8 moles of A would react with 4 moles of B to produce 2 moles of C. Since we only have 2.5 moles of C, B must be the limiting reactant.

Next, we can use stoichiometry again to determine the theoretical yield of C. 2 moles of C are produced for every 4 moles of B, so for 30 moles of B, we can produce 15 moles of C. Therefore, the percent yield is (2.5 moles/15 moles) x 100% = 16.7%. However, we need to take into account significant figures. Since we only have two significant figures in the given values, we must round the percent yield to 17%.

Finally, we can calculate the percent yield by dividing the actual yield (2.5 moles) by the theoretical yield (15 moles) and multiplying by 100%. Percent yield = (2.5 moles/15 moles) x 100% = 16.7% rounded to 17%. The closest answer choice is C, 83%, which is the complement of the percent yield. Therefore, the correct answer is C.

Question 8

When 1.00 × 10²² molecules of ammonia react with 7.00 × 10²² molecules of oxygen according to the chemical equation shown below,how many grams of nitrogen gas are produced? 4 NH₃(g)+ 3 O₂(g)→ 2 N₂(g)+ 6 H₂O(g)

Accepted Answer

1.00 × 10²² molecules of ammonia react with 7.00 × 10²² molecules of oxygen, which is the limiting reactant. Therefore, 1.00 × 10²² molecules of nitrogen gas are produced. The molar mass of nitrogen gas is 28.01 g/mol. Therefore, the mass of nitrogen gas produced is 1.00 × 10²² molecules × (28.01 g/mol) / (6.022 × 10²³ molecules/mol) = 0.464 g.

Question 9

A balanced equation has the same numbers and kinds of ________ on both sides of the reaction arrow.

Accepted Answer

The answer of A balanced equation has the same numbers...

Question 10

10 g of nitrogen is reacted with 5.0 g of hydrogen to produce ammonia according to the chemical equation shown below.Which one of the following statements is false? N₂(g)+ 3 H₂(g)→ 2 NH₃(g)

Accepted Answer

The theoretical yield of ammonia is not 15 g. The balanced equation shows that 1 mole of N2 reacts with 3 moles of H2 to produce 2 moles of NH3. Calculating the moles of N2 and H2, we find that N2 is the limiting reactant, and the theoretical yield of NH3 is approximately 12.14 g, not 15 g.

Question 11

What is the empirical formula for perfluoropropane if the compound contains 81% fluorine and 19% carbon by mass?

Accepted Answer

To find the empirical formula, we need to determine the mole ratio of carbon to fluorine. 
Assume we have 100 g of perfluoropropane:
- 81 g of fluorine would correspond to (81 g / 18.998 g/mol = 4.052 mol) of F
- 19 g of carbon would correspond to (19 g / 12.011 g/mol = 1.582 mol) of C
Now, we need to divide both numbers by the smaller one to obtain a mole ratio close to whole numbers:
4.052/1.582 ≈ 2.56/1
1.582/1.582 = 1/1
So, the empirical formula is C2F5, which corresponds to Choice C.

Question 12

Which substance is the limiting reactant when 8.0 g of sulfur reacts with 12 g of oxygen and 16 g of sodium hydroxide according to the following chemical equation? 2 S(s)+ 3 O₂(g)+ 4 NaOH(aq)→ 2 Na₂SO₄(aq)+ 2 H₂O(l)

Accepted Answer

To determine the limiting reactant, we first need to calculate the moles of each reactant. The molar masses are approximately 32 g/mol for sulfur (S), 32 g/mol for oxygen (O2), and 40 g/mol for sodium hydroxide (NaOH). Thus, we have:- 8.0 g S / 32 g/mol = 0.25 mol S- 12 g O2 / 32 g/mol = 0.375 mol O2- 16 g NaOH / 40 g/mol = 0.4 mol NaOHAccording to the stoichiometry of the given reaction, 2 moles of S react with 3 moles of O2 and 4 moles of NaOH. Therefore, for 0.25 moles of S, we would need 0.375 moles of O2 and 0.5 moles of NaOH. Since we only have 0.4 moles of NaOH, which is less than the required 0.5 moles, NaOH is the limiting reactant.

Question 13

Combustion analysis of 0.150 g of an unknown compound containing carbon,hydrogen,and oxygen produced 0.2607 g of CO₂ and 0.1418 g of H₂O.What is the empirical formula of the compound?

Accepted Answer

1) Calculate moles of CO: 
0.2607 g CO x (1 mol CO/57.97 g CO) = 0.004501 mol CO 
2) Calculate moles of H2O: 
0.1418 g H2O x (1 mol H2O/18.015 g H2O) = 0.007867 mol H2O 
3) Calculate moles of H: 
(2 mol H/1 mol H2O) x (0.007867 mol H2O) = 0.01573 mol H 
4) Calculate moles of C: 
(1 mol C/1 mol CO) x (0.004501 mol CO) = 0.004501 mol C 
5) Calculate moles of O: 
2 mol O/1 mol H2O x (0.007867 mol H2O) + 1 mol O/1 mol CO x (0.004501 mol CO) = 0.022235 mol O 
6) Divide by smallest number of moles (0.004501) to get empirical formula: 
H: (0.01573/0.004501) = 3.50 --> 4 
C: (0.004501/0.004501) = 1 
O: (0.022235/0.004501) = 4.93 --> 5 
Empirical formula: C1H4O5, which is equivalent to choice D.

Question 14

Which one of the following is not an empirical formula?

Accepted Answer

Empirical formulas represent the simplest whole-number ratio of elements in a compound. Options A, B, and C follow this rule, but D includes fractional subscripts, which are not allowed in empirical formulas.

Question 15

Which one of the following is an empirical formula?

Accepted Answer

The empirical formula represents the simplest whole-number ratio of elements in a compound. Option B, which appears to represent water (H2O) with its elements in a simple ratio, fits the definition of an empirical formula.

Question 16

Which substance is the limiting reactant when 16.0 g of sulfur reacts with 10.0 g of oxygen and 12.0 g of sodium hydroxide according to the following chemical equation? 2 S(s)+ 3 O₂(g)+ 4 NaOH(aq)→ 2 Na₂SO₄(aq)+ 2 H₂O(l)

Accepted Answer

To determine the limiting reactant, we first need to convert the masses of the reactants to moles using their molar masses. The molar mass of sulfur (S) is approximately 32.07 g/mol, oxygen (O2) is approximately 32.00 g/mol, and sodium hydroxide (NaOH) is approximately 40.00 g/mol.- For sulfur: $16.0 \, \text{g} \, S \times \frac{1 \, \text{mol} \, S}{32.07 \, \text{g} \, S} = 0.499 \, \text{mol} \, S$- For oxygen: $10.0 \, \text{g} \, O_2 \times \frac{1 \, \text{mol} \, O_2}{32.00 \, \text{g} \, O_2} = 0.3125 \, \text{mol} \, O_2$- For sodium hydroxide: $12.0 \, \text{g} \, NaOH \times \frac{1 \, \text{mol} \, NaOH}{40.00 \, \text{g} \, NaOH} = 0.300 \, \text{mol} \, NaOH$The chemical equation shows the stoichiometry of the reaction: 2 moles of S react with 3 moles of O2 and 4 moles of NaOH. To find the limiting reactant, we compare the mole ratio of the reactants to the coefficients in the balanced equation:- For sulfur: $0.499 \, \text{mol} \, S / 2 = 0.2495$- For oxygen: $0.3125 \, \text{mol} \, O_2 / 3 = 0.1042$- For sodium hydroxide: $0.300 \, \text{mol} \, NaOH / 4 = 0.075$The smallest ratio corresponds to sodium hydroxide, indicating it is the limiting reactant because it will be consumed first according to the stoichiometry of the reaction.

Question 17

What is the empirical formula of a substance that contains 2.64 g of C,0.444 g of H,and 3.52 g of O?

Accepted Answer

To find the empirical formula, convert the mass of each element to moles by dividing by their atomic masses (C: 12.01 g/mol, H: 1.008 g/mol, O: 16.00 g/mol). This gives: C: 2.64 g / 12.01 g/mol = 0.22 mol, H: 0.444 g / 1.008 g/mol = 0.44 mol, O: 3.52 g / 16.00 g/mol = 0.22 mol. The ratio of C:H:O is 0.22:0.44:0.22, which simplifies to 1:2:1. Therefore, the empirical formula is CH2O.

Question 18

When 5.00 × 10²² molecules of ammonia react with 4.00 × 10²² molecules of oxygen according to the chemical equation shown below,how many grams of nitrogen gas are produced? 4 NH₃(g)+ 3 O₂(g)→ 2 N₂(g)+ 6 H₂O(g)

Accepted Answer

The reaction is limited by the oxygen molecules. Using stoichiometry, 4.00 × 10^22 molecules of O2 will produce 2.67 × 10^22 molecules of N2. Converting to moles and then to grams gives approximately 1.16 g of N2.

Question 19

Combustion analysis of an unknown compound containing only carbon and hydrogen produced 1.1385 g of CO₂ and 0.5805 g of H₂O.What is the empirical formula of the compound?

Accepted Answer

The moles of carbon and hydrogen can be calculated from the masses of CO2 and H2O produced. The ratio of moles of carbon to hydrogen gives the empirical formula C2H5.

Question 20

9.0 g of iron is reacted with 9.0 g of water according to the chemical equation shown below.Which one of the following statements is false? 3 Fe(s)+ 4 H₂O(l)→ Fe₃O₄(s)+ 4 H₂(g)

Accepted Answer

To find the limiting reactant, we need to calculate the moles of each reactant.

Moles of Fe = 9.0 g / 56.85 g/mol = 0.1586 mol

Moles of H2O = 9.0 g / 18.015 g/mol = 0.4999 mol

The balanced equation shows that 3 moles of Fe react with 4 moles of H2O.

Since we have less than 3 moles of Fe and more than 4 moles of H2O, water is the excess reactant, and therefore the limiting reactant is Fe.

Now we can use stoichiometry to find the amount of FeS produced:

0.1586 mol Fe x (1 mol FeS/3 mol Fe) x (87.91 g FeS/mol) = 4.50 g FeS

Therefore, option D is false, as water is not the limiting reactant.

Quiz 3: Mass Relationships in Chemical Reactions

Which one of the following compounds contains the smallest percent oxygen by mass?

Which one of the following contains 52% carbon by mass?

When silver nitrate reacts with barium chloride,silver chloride and barium nitrate are formed.How many grams of silver chloride are formed when 10.8 g of silver nitrate reacts with 15.0 g of barium chloride?

Which one of the following is not an empirical formula?

What is the empirical formula of a substance that contains 12.0 g of C,2.00 g of H,and 5.33 g of O?

Balance the chemical equation given below,and calculate the volume of nitrogen monoxide gas produced when 8.00 g of ammonia is reacted with 9.00 g of oxygen at 25°C? The density of nitrogen monoxide at 25°C is 1.23 g/L. NH₃(g) + O₂(g) → NO(g) + H₂O(l)

Consider the following balanced reaction. 4A + 2B → 2C + D 8.0 moles of A and 30.moles of B react to form 2.5 moles of C.What is the percent yield of this reaction?

When 1.00 × 10²² molecules of ammonia react with 7.00 × 10²² molecules of oxygen according to the chemical equation shown below,how many grams of nitrogen gas are produced? 4 NH₃(g) + 3 O₂(g) → 2 N₂(g) + 6 H₂O(g)

A balanced equation has the same numbers and kinds of ________ on both sides of the reaction arrow.

10 g of nitrogen is reacted with 5.0 g of hydrogen to produce ammonia according to the chemical equation shown below.Which one of the following statements is false? N₂(g) + 3 H₂(g) → 2 NH₃(g)

What is the empirical formula for perfluoropropane if the compound contains 81% fluorine and 19% carbon by mass?

Which substance is the limiting reactant when 8.0 g of sulfur reacts with 12 g of oxygen and 16 g of sodium hydroxide according to the following chemical equation? 2 S(s) + 3 O₂(g) + 4 NaOH(aq) → 2 Na₂SO₄(aq) + 2 H₂O(l)

Combustion analysis of 0.150 g of an unknown compound containing carbon,hydrogen,and oxygen produced 0.2607 g of CO₂ and 0.1418 g of H₂O.What is the empirical formula of the compound?

Which one of the following is not an empirical formula?

Which one of the following is an empirical formula?

Which substance is the limiting reactant when 16.0 g of sulfur reacts with 10.0 g of oxygen and 12.0 g of sodium hydroxide according to the following chemical equation? 2 S(s) + 3 O₂(g) + 4 NaOH(aq) → 2 Na₂SO₄(aq) + 2 H₂O(l)

What is the empirical formula of a substance that contains 2.64 g of C,0.444 g of H,and 3.52 g of O?

When 5.00 × 10²² molecules of ammonia react with 4.00 × 10²² molecules of oxygen according to the chemical equation shown below,how many grams of nitrogen gas are produced? 4 NH₃(g) + 3 O₂(g) → 2 N₂(g) + 6 H₂O(g)

Combustion analysis of an unknown compound containing only carbon and hydrogen produced 1.1385 g of CO₂ and 0.5805 g of H₂O.What is the empirical formula of the compound?

9.0 g of iron is reacted with 9.0 g of water according to the chemical equation shown below.Which one of the following statements is false? 3 Fe(s) + 4 H₂O(l) → Fe₃O₄(s) + 4 H₂(g)

Quiz 3: Mass Relationships in Chemical Reactions

Which one of the following compounds contains the smallest percent oxygen by mass?

Which one of the following contains 52% carbon by mass?

When silver nitrate reacts with barium chloride,silver chloride and barium nitrate are formed.How many grams of silver chloride are formed when 10.8 g of silver nitrate reacts with 15.0 g of barium chloride?

Which one of the following is not an empirical formula?

What is the empirical formula of a substance that contains 12.0 g of C,2.00 g of H,and 5.33 g of O?

Balance the chemical equation given below,and calculate the volume of nitrogen monoxide gas produced when 8.00 g of ammonia is reacted with 9.00 g of oxygen at 25°C? The density of nitrogen monoxide at 25°C is 1.23 g/L. ________ NH3(g) + ________ O2(g) → ________ NO(g) + ________ H2O(l)

Consider the following balanced reaction. 4A + 2B → 2C + D 8.0 moles of A and 30.moles of B react to form 2.5 moles of C.What is the percent yield of this reaction?

When 1.00 × 1022 molecules of ammonia react with 7.00 × 1022 molecules of oxygen according to the chemical equation shown below,how many grams of nitrogen gas are produced? 4 NH3(g) + 3 O2(g) → 2 N2(g) + 6 H2O(g)

A balanced equation has the same numbers and kinds of ________ on both sides of the reaction arrow.

10 g of nitrogen is reacted with 5.0 g of hydrogen to produce ammonia according to the chemical equation shown below.Which one of the following statements is false? N2(g) + 3 H2(g) → 2 NH3(g)

What is the empirical formula for perfluoropropane if the compound contains 81% fluorine and 19% carbon by mass?

Which substance is the limiting reactant when 8.0 g of sulfur reacts with 12 g of oxygen and 16 g of sodium hydroxide according to the following chemical equation? 2 S(s) + 3 O2(g) + 4 NaOH(aq) → 2 Na2SO4(aq) + 2 H2O(l)

Combustion analysis of 0.150 g of an unknown compound containing carbon,hydrogen,and oxygen produced 0.2607 g of CO2 and 0.1418 g of H2O.What is the empirical formula of the compound?

Which one of the following is not an empirical formula?

Which one of the following is an empirical formula?

Which substance is the limiting reactant when 16.0 g of sulfur reacts with 10.0 g of oxygen and 12.0 g of sodium hydroxide according to the following chemical equation? 2 S(s) + 3 O2(g) + 4 NaOH(aq) → 2 Na2SO4(aq) + 2 H2O(l)

What is the empirical formula of a substance that contains 2.64 g of C,0.444 g of H,and 3.52 g of O?

When 5.00 × 1022 molecules of ammonia react with 4.00 × 1022 molecules of oxygen according to the chemical equation shown below,how many grams of nitrogen gas are produced? 4 NH3(g) + 3 O2(g) → 2 N2(g) + 6 H2O(g)

Combustion analysis of an unknown compound containing only carbon and hydrogen produced 1.1385 g of CO2 and 0.5805 g of H2O.What is the empirical formula of the compound?

9.0 g of iron is reacted with 9.0 g of water according to the chemical equation shown below.Which one of the following statements is false? 3 Fe(s) + 4 H2O(l) → Fe3O4(s) + 4 H2(g)

Balance the chemical equation given below,and calculate the volume of nitrogen monoxide gas produced when 8.00 g of ammonia is reacted with 9.00 g of oxygen at 25°C? The density of nitrogen monoxide at 25°C is 1.23 g/L. NH₃(g) + O₂(g) → NO(g) + H₂O(l)

When 1.00 × 10²² molecules of ammonia react with 7.00 × 10²² molecules of oxygen according to the chemical equation shown below,how many grams of nitrogen gas are produced? 4 NH₃(g) + 3 O₂(g) → 2 N₂(g) + 6 H₂O(g)

10 g of nitrogen is reacted with 5.0 g of hydrogen to produce ammonia according to the chemical equation shown below.Which one of the following statements is false? N₂(g) + 3 H₂(g) → 2 NH₃(g)

Which substance is the limiting reactant when 8.0 g of sulfur reacts with 12 g of oxygen and 16 g of sodium hydroxide according to the following chemical equation? 2 S(s) + 3 O₂(g) + 4 NaOH(aq) → 2 Na₂SO₄(aq) + 2 H₂O(l)

Combustion analysis of 0.150 g of an unknown compound containing carbon,hydrogen,and oxygen produced 0.2607 g of CO₂ and 0.1418 g of H₂O.What is the empirical formula of the compound?

Which substance is the limiting reactant when 16.0 g of sulfur reacts with 10.0 g of oxygen and 12.0 g of sodium hydroxide according to the following chemical equation? 2 S(s) + 3 O₂(g) + 4 NaOH(aq) → 2 Na₂SO₄(aq) + 2 H₂O(l)

When 5.00 × 10²² molecules of ammonia react with 4.00 × 10²² molecules of oxygen according to the chemical equation shown below,how many grams of nitrogen gas are produced? 4 NH₃(g) + 3 O₂(g) → 2 N₂(g) + 6 H₂O(g)

Combustion analysis of an unknown compound containing only carbon and hydrogen produced 1.1385 g of CO₂ and 0.5805 g of H₂O.What is the empirical formula of the compound?

9.0 g of iron is reacted with 9.0 g of water according to the chemical equation shown below.Which one of the following statements is false? 3 Fe(s) + 4 H₂O(l) → Fe₃O₄(s) + 4 H₂(g)