Q: Which of the following pairs of compounds are both insoluble in water and contain calcium?

$$\mathrm{$$CaCO_3$$}$$ \ \text{and} \ \mathrm{$$CaSO_4$$}$

Question 1

A sample of sodium chloride (NaCl) has a density of $$4.28 \ \mathrm{g/cm^3$}. $$How many oxygen atoms are present in $$12.0 \ \mathrm{cm^3$} of $$sodium iodate ($$\mathrm{$$NaIO_3$$}$$)? (Atomic masses: Na = 22.99, I = 126.90, O = 16.00)

Accepted Answer

$$1.36 	imes 10$$^{24}$$

Question 2

Which of the following statements best describes the difference between precision and accuracy?

Accepted Answer

Precision refers to how close repeated measurements are to each other, while accuracy refers to how close a measured value is to the true value.

Question 3

A compound is found to contain 78.9% C, 7.06% H, and 14.0% O by mass. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{C_6H_7O}$$

Question 4

Iron has four stable isotopes. If the average atomic mass of iron is $$55.85 \ \mathrm{u}$$, which isotope is most abundant?

Accepted Answer

$$\mathrm{^{56}Fe}$$

Question 5

Chlorine reacts with potassium iodide according to the equation: $$\mathrm{Cl_2$ + 2KI \rightarrow 2KCl + I_2$}. $$How many grams of KI are required to completely react with $$1.20 \ \mathrm{g} of$$ $$\mathrm{Cl_2$}$$? (Molar masses: Cl$$_2 = 70.90 g/$$mol, KI = 166.00 g/mol)

Accepted Answer

$$5.62 \ \mathrm{g}$$

Question 6

A $$0.500 \ \mathrm{M}$$ solution of potassium chloride is to be prepared. How many grams of potassium chloride are required to make $$1.00 \ \mathrm{L} of $$solution? (Molar mass of KCl = 74.55 g/mol)

Accepted Answer

$$37.3 \ \mathrm{g}$$

Question 7

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of $$\mathrm{$$AgNO_3$$}$$ and $$\mathrm{NaCl}$$?

Accepted Answer

$$\mathrm{Ag^+ (aq) + Cl^- (aq) \rightarrow AgCl (s)}$$

Question 8

A $$20.0 \ \mathrm{mL}$$ sample of $$6.00 \ \mathrm{M}$$ NaOH is added to a $$250.0 \ \mathrm{mL}$$ volumetric flask and diluted to the mark with water. What is the final concentration of NaOH?

Accepted Answer

$$0.48 \ \mathrm{M}$$

Question 9

Which of the following pairs of compounds are both insoluble in water and contain calcium?

Accepted Answer

$$\mathrm{$$CaCO_3$$}$$ \ 	ext{and} \ \mathrm{$$CaSO_4$$}$

Question 10

A $$12.00 \ \mathrm{g}$$ sample of a compound is combusted in oxygen to form $$17.03 \ \mathrm{g} of$$ $$\mathrm{CO_2$}$$ and $$5.23 \ \mathrm{g} of$$ $$\mathrm{H_2O}. $$What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{C_2H_6O}$$

Question 11

Which of the following is the correct balanced equation for the combustion of methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

$$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}$$

Question 12

If $$3.40 \ \mathrm{g} of $$ammonia ($$\mathrm{NH_3$}) is $$produced from $$1.50 \ \mathrm{g} of $$hydrogen and excess nitrogen, what is the percent yield? (Molar mass: $$\mathrm{NH_3$} = 17.03 g/$$mol, $$\mathrm{H_2$} = 2.02 g/$$mol)

Accepted Answer

$$99.9\%$$

Question 13

Which of the following is the correct name for $$\mathrm{$$KClO_3$$}$$?

Accepted Answer

Potassium chlorate

Question 14

Which of the following best describes a limiting reactant in a chemical reaction?

Accepted Answer

The reactant that determines the amount of product formed

Question 15

A $$0.350 \ \mathrm{M}$$ solution of sodium bicarbonate ($$\mathrm{$$NaHCO_3$$}) is to be $$prepared. If you weigh out $$14.7 \ \mathrm{g} of$$ $$\mathrm{$$NaHCO_3$$}$$, what size volumetric flask should you use? (Molar mass $$\mathrm{$$NaHCO_3$$} = 84.01 g/$$mol)

Accepted Answer

$$0.25 \ \mathrm{L}$$

Question 16

Which of the following is the correct molecular formula for a compound with an empirical formula of $$\mathrm{CH_2O}$$ and a molar mass of $$180 \ \mathrm{g/mol}$$?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$}$$

Question 17

Which of the following is the correct formula for lead(II) acetate?

Accepted Answer

$$\mathrm{Pb(C_2H_3O_2)_2}$$

Question 18

Which of the following is a strong electrolyte when dissolved in water?

Accepted Answer

$$\mathrm{NaCl}$$

Question 19

Which of the following is the correct total ionic equation for the reaction of $$\mathrm{Hg_2$(C_2O_4)_2}$$ and $$\mathrm{LiI} in $$water?

Accepted Answer

$$\mathrm{Hg_2$^{2+} (aq) + 2C_2O_4$$^{2-}$$ (aq) + 2Li^+ (aq) + 2I^- (aq) \rightarrow Hg_2I_2 (s) + 2Li^+ (aq) + 2C_2O_4$$^{2-}$$ (aq)}$$

General Chemistry Exam 1 Preparation: Key Concepts and Practice

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