Q: Which of the following conversion factors would you use to determine the number of moles of Fe needed to produce a known number of moles of Fe$$_2O$_3 in $$the reaction $$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$?

$$\frac{4\ \text{moles of Fe}}{2\ \text{moles of Fe}_2O_3}$$

Q: Refer to the heating curve of water. What does step 4 represent?

The temperature of liquid water remains at $$100\ ^\circ\text{C} as it $$boils.

Q: A solution has $$[H_3O^+] = 2.0 \times 10$$^{-4}$$\ \text{M}. $$What is the $$[OH^-] in $$this solution? ($$K_w = 1.0 \times 10$$^{-14}$$)

$$5.0 \times 10$$^{-11}$$\ \text{M}$$

Question 1

Which of the following conversion factors would you use to determine the number of moles of Fe needed to produce a known number of moles of Fe$$_2O$_3 in $$the reaction $$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$?

Accepted Answer

$$\frac{4\ 	ext{moles of Fe}}{2\ 	ext{moles of Fe}_2O_3}$$

Question 2

Refer to the heating curve of water. What does step 4 represent?

Accepted Answer

The temperature of liquid water remains at $$100\ ^\circ	ext{C} as it $$boils.

Question 3

Which of the following statements about the Group 1A (alkali metals) is FALSE?

Accepted Answer

Most of them are liquids at room temperature.

Question 4

A patient weighing 55 kg needs a diagnostic test with I-131 at a dosage of $$4.2\ \mu	ext{Ci/kg}. $$How many mCi should be administered? ($$1\ 	ext{mCi} = 1000\ \mu	ext{Ci})$$

Accepted Answer

0.23 mCi

Question 5

Which of the following best describes the process occurring in the Sun, where hydrogen nuclei combine to form a larger nucleus and release energy?

Accepted Answer

Fusion

Question 6

What is the molarity of a solution that contains 17 g of NH$$_3 in 0.50 L of $$solution? (Molar mass of NH$$_3 = 17 g/$$mol)

Accepted Answer

2.0 M

Question 7

Which of the following compounds contains a polar covalent bond?

Accepted Answer

HCl

Question 8

What is the value of the equilibrium constant $$K_c$$ for the reaction $$	ext{PCl}_5(g) ightleftharpoons 	ext{PCl}_3(g) + 	ext{Cl}_2(g) if$$ $$[	ext{PCl}_5] = 0.75\ 	ext{M}$$, $$[	ext{PCl}_3] = 0.50\ 	ext{M}$$, and $$[	ext{Cl}_2] = 0.25\ 	ext{M}$$?

Accepted Answer

$$0.167$$

Question 9

Which of the following is the correct formula for a compound formed from aluminum and oxygen?

Accepted Answer

Al$$_2O$_3$$

Question 10

A solution has $$[H_3O^+] = 2.0 	imes 10$$^{-4}$$\ 	ext{M}. $$What is the $$[OH^-] in $$this solution? ($$K_w = 1.0 	imes 10$$^{-14}$$)

Accepted Answer

$$5.0 	imes 10$$^{-11}$$\ 	ext{M}$$

Question 11

Which of the following would be soluble in hexane (C$$_6H$_{14}$$), but not in water?

Accepted Answer

Mineral oil

Question 12

Which of the following is the strongest acid?

Accepted Answer

HCl

Question 13

What is the mass of a sample of O$$_2$$ gas, which has a pressure of 762 mmHg, at a temperature of $$27\ ^\circ	ext{C}$$, in a volume of 100 mL? ($$R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K}$$, 1 atm = 760 mmHg, molar mass O$$_2 = 32 g/$$mol)

Accepted Answer

0.130 g

Question 14

Which of the following best describes the movement of solvent in osmosis?

Accepted Answer

Solvent moves through a semipermeable membrane into an area of higher solute concentration.

Question 15

Which of the following is NOT a way to increase the rate of a chemical reaction?

Accepted Answer

Decreasing the temperature

Question 16

Which of the following best describes Avogadro's number?

Accepted Answer

The number of particles in 1 mole of a substance.

Question 17

Which of the following is the correct rearrangement of the ideal gas law to solve for $$n$$?

Accepted Answer

$$n = \frac{PV}{RT}$$

Question 18

Which of the following best describes the relationship between the strength of an acid and its conjugate base?

Accepted Answer

The stronger the acid, the weaker the conjugate base.

Stoichiometric Conversions and Molar Ratios in Chemical Reactions

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