Q: A sample of gas at 1.00 atm and 273 K occupies 22.4 L. If the temperature is increased to 546 K at constant pressure, what will be the new volume?

$$V_2$$ = $$V_1$$ \times \frac{$$T_2$$}{$$T_1$$} = 22.4 \times \frac{546}{273} = 44.8$$ L

Q: A solution is prepared by dissolving 5.00 g of NaCl in enough water to make 250.0 mL of solution. What is the molarity of the solution? ($$M_{NaCl} = 58.44 g/$$mol)

$$M = \frac{5.00\ \text{g}}{58.44\ \text{g/mol}} \div 0.250\ \text{L} = 0.342 M$$

Q: A sample of calcium carbonate ($$CaCO_3) $$decomposes according to the following reaction: $$CaCO_3 (s$$) \rightarrow CaO (s) + $$CO_2 (g$$)$$. If 10.0 g of $$CaCO_3$$ is decomposed, how many grams of CO_2$ are produced? (M$$_{$$CaCO_3$$} = 100.09$$ g/mol, M$$_{$$CO_2$$} = 44.01$$ g/mol)

$$10.0\ \text{g} \times \frac{1\ \text{mol}}{100.09\ \text{g}} \times \frac{44.01\ \text{g}}{1\ \text{mol}} = 4.40 g$$

Question 1

Which of the following best describes the difference between a compound and a mixture?

Accepted Answer

A compound consists of two or more elements chemically bonded in fixed proportions, while a mixture consists of two or more substances physically combined in variable proportions.

Question 2

A student measures the mass of a sample as 12.34 g and its volume as 4.56 mL. What is the density of the sample, and which significant figures rule applies?

Accepted Answer

Density $$= \frac{12.34}{4.56} = 2.71 g/mL$$, rounded to 3 significant figures because division uses the least number of significant figures.

Question 3

Which statement about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 4

Which of the following is the correct electron configuration for a neutral atom of oxygen ($$Z=8$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^4$$

Question 5

A sample of gas at 1.00 atm and 273 K occupies 22.4 L. If the temperature is increased to 546 K at constant pressure, what will be the new volume?

Accepted Answer

$$V_2$$ = $$V_1$$ 	imes \frac{$$T_2$$}{$$T_1$$} = 22.4 	imes \frac{546}{273} = 44.8$$ L

Question 6

Which of the following best explains why ionic compounds tend to have high melting points?

Accepted Answer

Ionic compounds have strong electrostatic attractions between oppositely charged ions.

Question 7

Which of the following is a correct balanced chemical equation for the combustion of methane ($$CH_4$$)?

Accepted Answer

$$CH_4 + 2O_2$$ \rightarrow $$CO_2 + 2H_2O$

Question 8

A solution is prepared by dissolving 5.00 g of NaCl in enough water to make 250.0 mL of solution. What is the molarity of the solution? ($$M_{NaCl} = 58.44 g/$$mol)

Accepted Answer

$$M = \frac{5.00\ 	ext{g}}{58.44\ 	ext{g/mol}} \div 0.250\ 	ext{L} = 0.342 M$$

Question 9

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have the same number of valence electrons.

Question 10

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of NaCl and AgNO$$_3$$?

Accepted Answer

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

Question 11

A sample of calcium carbonate ($$CaCO_3) $$decomposes according to the following reaction: $$CaCO_3 (s$$) \rightarrow CaO (s) + $$CO_2 (g$$)$$. If 10.0 g of $$CaCO_3$$ is decomposed, how many grams of CO_2$ are produced? (M$$_{$$CaCO_3$$} = 100.09$$ g/mol, M$$_{$$CO_2$$} = 44.01$$ g/mol)

Accepted Answer

$$10.0\ 	ext{g} 	imes \frac{1\ 	ext{mol}}{100.09\ 	ext{g}} 	imes \frac{44.01\ 	ext{g}}{1\ 	ext{mol}} = 4.40 g$$

Question 12

Which of the following best describes the process of reduction in a redox reaction?

Accepted Answer

Reduction is the gain of electrons by a species.

Question 13

Which of the following molecules is polar?

Accepted Answer

$$NH_3$$

Question 14

Which of the following statements about intermolecular forces is correct?

Accepted Answer

London dispersion forces are present in all molecules, regardless of polarity.

Question 15

A patient receives an intravenous solution containing 0.9% NaCl (normal saline). What type of solution is this relative to human blood cells?

Accepted Answer

Isotonic

Question 16

Which of the following is the correct formula for calculating the percent composition by mass of an element in a compound?

Accepted Answer

$$\frac{	ext{mass of element in 1 mol of compound}}{	ext{molar mass of compound}} 	imes 100\%$$

Question 17

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

Metals have delocalized electrons that can move freely throughout the lattice.

Question 18

A chemical reaction has $$\Delta H = -125 kJ. $$Which statement is true about this reaction?

Accepted Answer

The reaction is exothermic and releases heat to the surroundings.

Question 19

Which of the following is the correct expression for the ideal gas law?

Accepted Answer

$$PV = nRT$$

CHM 1001: Principles of Chemistry I – Syllabus and Course Structure

Guida di studio - Domande di pratica

Study guide - Flashcard