Q: Which molar conversion factor would be used to find 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 shown. What does step 4 represent?

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

Q: How many atoms of gold are present in $$1.30$$ moles of gold?

$$7.83 \times 10$$^{23}$$ atoms

Question 1

Which molar conversion factor would be used to find 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 shown. 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 properties is NOT a characteristic of the Group 1A (1) elements (alkali metals)?

Accepted Answer

Most of them are liquids at room temperature.

Question 4

A patient is prescribed a dosage of I-131 at $$4.2\ \mu	ext{Ci}/	ext{kg} of $$body weight. How many mCi should be given to a $$55\ 	ext{kg}$$ patient? ($$1\ 	ext{mCi} = 1000\ \mu	ext{Ci})$$

Accepted Answer

0.23 mCi

Question 5

The half-life of Iodine-123 is $$13$$ hours. If $$50.0 mg of I-123 $$were prepared at $$8:00 A.M. on $$Monday, how many mg remain at $$10:00 A.M. on $$the following day?

Accepted Answer

12.5 mg

Question 6

Which of the following types of radiation has the highest energy?

Accepted Answer

gamma rays

Question 7

What is the correct formula for a compound formed from the elements Al and O?

Accepted Answer

Al$$_2O$_3$$

Question 8

How many atoms of gold are present in $$1.30$$ moles of gold?

Accepted Answer

$$7.83 	imes 10$$^{23}$$ atoms

Question 9

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

Accepted Answer

2.0 M

Question 10

For the reaction $$2H_2O(l) + 137\ 	ext{kcal} ightarrow 2H_2(g) + O_2$(g)$$, how many kcal are needed to react $$75.0\ 	ext{g} H$_2O(l$$)? (Molar mass of H$$_2O$$ = $$18\ 	ext{g/mol})$$

Accepted Answer

571 kcal

Question 11

According to Henry's law, the solubility of a gas in a liquid:

Accepted Answer

increases as the gas pressure above the liquid increases.

Question 12

What is the [OH$$^-$$] in a solution that has a [H$$_3O$^+$$] $$= 2.0 	imes 10$$^{-4}$$ M? (K_w = 1.0$$ 	imes $$10^{-14})$$

Accepted Answer

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

Question 13

A solution with a pH of $$4 is$$:

Accepted Answer

moderately acidic.

Question 14

Which of the following is the strongest acid?

Accepted Answer

HCl

Question 15

The stronger the acid, the ________ the conjugate base.

Accepted Answer

weaker

Question 16

What is the [H$$_3O$^+$$] of a solution with pH $$= 2.0$$?

Accepted Answer

$$1 	imes 10$$^{-2}$$ M

Question 17

Which measurement describes the pressure of a gas?

Accepted Answer

725 torr

Question 18

When the ideal gas law is rearranged to solve for $$n$$, what is the correct expression?

Accepted Answer

$$\frac{PV}{RT}$$

Question 19

Which of the following compounds contains a polar covalent bond?

Accepted Answer

HCl

Stoichiometric Conversions and Molar Ratios in Chemical Reactions

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