Q: A candy bar contains 225 Cal of nutritional energy. How many joules does it contain? (1 Cal = 1000 cal, 1 cal = 4.184 J)

$$225 \times 1000 \times 4.184 = 941,400 J$$

Q: A 2.5 g sample of gallium is heated from $$25.0^\circ C to$$ $$29.9^\circ C. If $$the specific heat capacity of gallium is $$0.372 \ \mathrm{J/g}^\circ C$$, how much heat is absorbed?

$$q = m \times C \times \Delta T = 2.5 \times 0.372 \times (29.9 - 25.0) = 4.6 J$$

Question 1

Which of the following best describes a crystalline solid?

Accepted Answer

Atoms or molecules are arranged in a geometric pattern with long-range repeating order.

Question 2

A sample of matter is observed to have a definite volume but takes the shape of its container. Which state of matter is this sample most likely in?

Accepted Answer

Liquid

Question 3

Which of the following is an example of a chemical property?

Accepted Answer

The flammability of gasoline

Question 4

Which of the following changes is a chemical change?

Accepted Answer

Iron rusting in moist air

Question 5

A mixture of sand and salt is an example of which type of matter?

Accepted Answer

Heterogeneous mixture

Question 6

Which of the following statements about the law of conservation of mass is correct?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 7

Which of the following is the correct formula to convert Celsius temperature to Kelvin?

Accepted Answer

$$K = ^\circ C + 273.15$$

Question 8

A candy bar contains 225 Cal of nutritional energy. How many joules does it contain? (1 Cal = 1000 cal, 1 cal = 4.184 J)

Accepted Answer

$$225 	imes 1000 	imes 4.184 = 941,400 J$$

Question 9

Which of the following best describes an exothermic reaction?

Accepted Answer

A reaction that releases energy to the surroundings

Question 10

Which of the following is a correct statement about temperature and heat?

Accepted Answer

Temperature is a measure of the thermal energy of matter, while heat is the transfer of thermal energy due to a temperature difference.

Question 11

A 2.5 g sample of gallium is heated from $$25.0^\circ C to$$ $$29.9^\circ C. If $$the specific heat capacity of gallium is $$0.372 \ \mathrm{J/g}^\circ C$$, how much heat is absorbed?

Accepted Answer

$$q = m 	imes C 	imes \Delta T = 2.5 	imes 0.372 	imes (29.9 - 25.0) = 4.6 J$$

Question 12

Which of the following is a homogeneous mixture?

Accepted Answer

Sweetened tea

Question 13

Which of the following is NOT a pure substance?

Accepted Answer

Air

Question 14

Which of the following best describes the difference between a physical and a chemical change?

Accepted Answer

A physical change does not alter the composition of a substance, while a chemical change results in a new substance.

Question 15

Which of the following is the correct relationship for converting Fahrenheit to Celsius?

Accepted Answer

$$^\circ C = \frac{^\circ F - 32}{1.8}$$

Question 16

Which of the following is a correct statement about the compressibility of gases?

Accepted Answer

Gases are compressible because their atoms or molecules are far apart and not in contact with each other.

Question 17

Which of the following is the correct energy conversion factor between calories and joules?

Accepted Answer

$$1 \ \mathrm{cal} = 4.184 \ \mathrm{J}$$

Question 18

Which of the following best describes potential energy in a chemical context?

Accepted Answer

Potential energy is the energy associated with the position or composition of particles in a chemical system.

Question 19

Which of the following is true about the Kelvin temperature scale?

Accepted Answer

It assigns 0 K to absolute zero, the temperature at which molecular motion virtually stops.

Question 20

A chemical reaction absorbs 150 kJ of energy from its surroundings. Which term best describes this reaction?

Accepted Answer

Endothermic

Chapter 3: Matter and Energy – Study Notes for Introductory Chemistry

Guida di studio - Domande di pratica

Study guide - Flashcard