Q: Which of the following is the correct percent yield formula?

$$\frac{\text{actual yield}}{\text{theoretical yield}} \times 100$$

Question 1

A compound contains 28.19% nitrogen by mass. What is the percent by mass of phosphorus in ammonium phosphate, $$(NH_4$)_3PO_4$$?

Accepted Answer

$$42.05\%$$

Question 2

Which element in pigment green (CuCl$$_2$$\cdot$$2H_2$O) has the greatest mass percentage?

Accepted Answer

Chlorine

Question 3

A compound has an empirical formula of $$CH_2O$$ and a molar mass of $$120\ \mathrm{g/mol}. $$What is its molecular formula?

Accepted Answer

$$C_4H_8O_4$$

Question 4

A sample contains 52.14% C, 13.13% H, and 34.73% O by mass. What is the empirical formula of the compound?

Accepted Answer

$$C_2H_6O$$

Question 5

Which of the following is the correct balanced equation for the complete combustion of ethanol, $$C_2H_5OH$$?

Accepted Answer

$$C_2H_5OH + 3O_2 \rightarrow 2CO_2 + 3H_2O$$

Question 6

How many moles of oxygen gas are produced by the decomposition of $$5.8\ \mathrm{mol} of $$water according to the equation $$2H_2O(l) \rightarrow 2H_2(g) + O_2$(g)$$?

Accepted Answer

$$2.9\ \mathrm{mol}$$

Question 7

A student combusts a $$1.125\ \mathrm{g}$$ sample of an unknown compound containing only C, H, and O. The combustion produces $$2.125\ \mathrm{g} of CO$_2$$ and $$0.818\ \mathrm{g} of H$_2O. $$What is the empirical formula of the compound?

Accepted Answer

$$CH_2O$$

Question 8

Which of the following statements about limiting reactants is correct?

Accepted Answer

The limiting reactant is completely consumed during the reaction.

Question 9

Calculate the percent yield if $$8.21\ \mathrm{g} of $$product is obtained from a reaction with a theoretical yield of $$10.0\ \mathrm{g}.$$

Accepted Answer

$$82.1\%$$

Question 10

When balancing the equation $$Fe_2O_3 + C \rightarrow Fe + CO_2$, what is the coefficient in front of Fe$?

Accepted Answer

$$4$$

Question 11

A compound contains only carbon and hydrogen, is $$85.6\%$$ carbon by mass, and has a molar mass of $$70\ \mathrm{g/mol}. $$What is its molecular formula?

Accepted Answer

$$C_5H_{10}$$

Question 12

Which of the following is NOT a diatomic element in its natural state?

Accepted Answer

Carbon

Question 13

If $$1.651\ \mathrm{g} Ag $$and $$0.1224\ \mathrm{g} O $$are decomposed from a sample, what is the empirical formula of the compound?

Accepted Answer

$$Ag_2O$$

Question 14

Which of the following best describes the law of conservation of mass as it applies to chemical reactions?

Accepted Answer

The total mass of reactants equals the total mass of products.

Question 15

A $$2.677\ \mathrm{g}$$ sample of barium reacts with $$3.115\ \mathrm{g} of $$bromine to form a compound. What is the empirical formula?

Accepted Answer

$$BaBr_2$$

Question 16

Which of the following is the correct sequence for solving a stoichiometry problem starting with mass of reactant A and ending with mass of product B?

Accepted Answer

Mass A $$\rightarrow$$ Moles A $$\rightarrow$$ Moles B $$\rightarrow$$ Mass B

Question 17

A white powder is analyzed and found to have an empirical formula of $$P_2O_5. $$The compound has a molar mass of $$283.88\ \mathrm{g/mol}. $$What is the compound's molecular formula?

Accepted Answer

$$P_4O_{10}$$

Question 18

Which of the following is the correct percent yield formula?

Accepted Answer

$$\frac{	ext{actual yield}}{	ext{theoretical yield}} 	imes 100$$

Question 19

If $$150.0\ \mathrm{g} Al $$reacts with $$266.89\ \mathrm{g} I$_2 to $$form $$150.0\ \mathrm{g}$$ AlI$$_3$$, what is the percent yield?

Accepted Answer

$$93.7\%$$

Chapter 3 Student Notes

Guida di studio - Domande di pratica

Study guide - Flashcard