Question 1

A 13.6-gram sample of a compound composed of carbon, hydrogen, and oxygen produces 6.684 grams of carbon dioxide ($$CO_2) $$and 3.290 grams of water ($$H_2O) $$during combustion analysis. What is its empirical formula?

Accepted Answer

$$C_2H_6O$$

Question 2

A sample of $$CuSO_4$$ \cdot xH_2O$$ is heated to drive off the water. When the resulting anhydrous salt is weighed, its mass is 0.18 grams. What is the value of x$ in the formula for the hydrate if the original mass was 0.24 grams?

Accepted Answer

$$x = 5$$

Question 3

How many atoms of oxygen are present in 60.0 grams of potassium chlorate ($$KClO_3$$)?

Accepted Answer

$$3.60 	imes 10$$^{24}$$

Question 4

A certain nitrogen-oxygen compound contains 36.84% nitrogen by mass and has a molar mass between 120 and 160 g/mol. What is the molecular formula of the compound?

Accepted Answer

$$N_2O_4$$

Question 5

Rutile ($$TiO_2) $$can be produced from ilmenite ($$FeTiO_3) $$via the following unbalanced reaction: $$FeTiO_3$$ + $$Cl_2 + C$$ \rightarrow $$FeCl_3$$ + $$TiCl_4 + CO$. If 379 g of ore containing 18% ilmenite ($$FeTiO_3$$) is used, what is the mass of rutile ($$TiO_2$$) that may be produced?

Accepted Answer

$$176 g$$

Question 6

If 40 grams of $$C_4H_{10}$$ were produced when 40 grams of $$C_4H_{10}$$ were combusted in excess oxygen, what is the percent yield of the combustion reaction?

Accepted Answer

$$88.4\%$$

Question 7

A tablet contains vitamin C ($$C_6H_8O_6$$, 176.12 g/mol) content in a tablet, two stepwise reactions were performed:
$$C_6H_8O_6 + Br_2$ \rightarrow C_6H_6O_6 + 2HBr$$
$$HBr + NaOH \rightarrow NaBr + H_2O
If a $$NaOH solution was used to titrate 1.00 g of vitamin C and the titration required 16.2 mL of 0.100 M NaOH, what is the percent mass of vitamin C in the tablet?

Accepted Answer

$$15.1\%$$

Question 8

Solid calcium oxide reacts with solid ammonium chloride to produce gaseous ammonia, gaseous water, and solid calcium chloride. If 12 grams of calcium oxide were reacted with 16.2 grams of ammonium chloride, what maximum mass of ammonia could be produced?

Accepted Answer

$$5.16 g$$

Question 9

For the previous problem, what mass of excess reactant remains?

Accepted Answer

$$7.98 g$$

Question 10

Which of the following is true about physical and chemical changes?

Accepted Answer

Chemical changes are generally revealed by altering the temperature of the system

Question 11

Which of the following is NOT true about molecular and atomic structure?

Accepted Answer

HCl is a homonuclear diatomic molecule but not a compound

Question 12

Which of the following equations is balanced and correctly represents the acid dissociation of acetic acid in water?

Accepted Answer

$$CH_3COOH + H_2O \rightarrow CH_3COO^- + H_3O^+$$

Question 13

A 0.013 g sample of $$ZnSO_4$$ \cdot xH_2O$$ is dissolved in an aqueous solution containing excess $$BaCl_2$$. The mass of $$BaSO_4$$ formed is 0.00822 g. What is the value of x$ in $$ZnSO_4$$ \cdot xH_2O$$?

Accepted Answer

$$x = 5$$

Question 14

Which of the following has the largest numerical value?

Accepted Answer

Number of atoms in 1 mole of $$^{23}Na$$

Question 15

An unknown substance has a density of $$0.983 	ext{ g/cm}^3. $$What is this density in $$	ext{kg/m}^3$$?

Accepted Answer

$$9.83 	imes 10^2$

Question 16

If a metal foil weighs 10.94 lbs, is 0.0100 mm thick, and has a top surface area of 525 $$	ext{ft}^2$$, what is the density of the foil?

Accepted Answer

$$8.25 	ext{ g/cm}^3$$

Question 17

Which element is oxidized in the following reaction? $$Mg + 2H_2O \rightarrow Mg(OH)_2 + H_2$

Accepted Answer

Mg

Question 18

Which of the following is NOT a correct formula pair?

Accepted Answer

Aluminum fluoride, $$AlBr_3$$

General Chemistry Exam and Practice Questions: Stoichiometry, Solutions, Chemical Reactions, and Atomic Structure

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