Q: A student heats 50.0 g of water from $$20.0\ ^\circ\mathrm{C} to$$ $$100.0\ ^\circ\mathrm{C}. If $$the specific heat of water is $$4.18\ \mathrm{J}/(\mathrm{g}\cdot ^\circ\mathrm{C})$$, how much heat is absorbed?

$$Q = m \cdot c \cdot \Delta T = 50.0 \times 4.18 \times 80.0 = 16,720\ \mathrm{J}$$

Q: A cup of whole milk contains 13 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. Using the energy values (carbohydrate: $$4\ \mathrm{kcal/g}$$, fat: $$9\ \mathrm{kcal/g}$$, protein: $$4\ \mathrm{kcal/g}$$), how many kilocalories does a cup of whole milk contain?

$$13 \times 4 + 9.0 \times 9 + 9.0 \times 4 = 52 + 81 + 36 = 169\ \mathrm{kcal}$$

Q: A sample of metal with a mass of $$24.8\ \mathrm{g}$$ absorbs $$275\ \mathrm{J} of $$energy, causing its temperature to rise from $$20.0\ ^\circ\mathrm{C} to$$ $$36.0\ ^\circ\mathrm{C}. $$What is the specific heat of the metal?

$$c = \frac{q}{m \cdot \Delta T} = \frac{275}{24.8 \times 16.0} = 0.693\ \mathrm{J}/(\mathrm{g}\cdot ^\circ\mathrm{C})$$

Q: How many kilojoules are released when $$50.0\ \mathrm{g} of $$steam condenses at $$100\ ^\circ\mathrm{C}$$? (Heat of vaporization for water is $$2260\ \mathrm{J/g})$$

$$Q = 50.0 \times 2260 = 113,000\ \mathrm{J} = 113\ \mathrm{kJ}$$

Question 1

Which of the following best describes a compound?

Accepted Answer

A substance composed of two or more elements combined in a fixed ratio.

Question 2

Which of the following is an example of a homogeneous mixture?

Accepted Answer

Brass (an alloy of copper and zinc)

Question 3

A student heats 50.0 g of water from $$20.0\ ^\circ\mathrm{C} to$$ $$100.0\ ^\circ\mathrm{C}. If $$the specific heat of water is $$4.18\ \mathrm{J}/(\mathrm{g}\cdot ^\circ\mathrm{C})$$, how much heat is absorbed?

Accepted Answer

$$Q = m \cdot c \cdot \Delta T = 50.0 	imes 4.18 	imes 80.0 = 16,720\ \mathrm{J}$$

Question 4

Which of the following changes is a chemical change?

Accepted Answer

Iron rusting in an old car

Question 5

A cup of whole milk contains 13 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. Using the energy values (carbohydrate: $$4\ \mathrm{kcal/g}$$, fat: $$9\ \mathrm{kcal/g}$$, protein: $$4\ \mathrm{kcal/g}$$), how many kilocalories does a cup of whole milk contain?

Accepted Answer

$$13 	imes 4 + 9.0 	imes 9 + 9.0 	imes 4 = 52 + 81 + 36 = 169\ \mathrm{kcal}$$

Question 6

Which of the following statements about the Kelvin temperature scale is correct?

Accepted Answer

Absolute zero is $$0\ \mathrm{K}$$, and there are no negative values.

Question 7

How many calories are obtained from a pat of butter if it provides $$150\ \mathrm{J} of $$energy when metabolized? ($$1\ \mathrm{cal} = 4.184\ \mathrm{J})$$

Accepted Answer

$$150 \div 4.184 = 35.9\ \mathrm{cal}$$

Question 8

Which of the following best describes the energy transformation when water at the top of a dam is released and flows downward?

Accepted Answer

Potential energy is converted to kinetic energy.

Question 9

A sample of metal with a mass of $$24.8\ \mathrm{g}$$ absorbs $$275\ \mathrm{J} of $$energy, causing its temperature to rise from $$20.0\ ^\circ\mathrm{C} to$$ $$36.0\ ^\circ\mathrm{C}. $$What is the specific heat of the metal?

Accepted Answer

$$c = \frac{q}{m \cdot \Delta T} = \frac{275}{24.8 	imes 16.0} = 0.693\ \mathrm{J}/(\mathrm{g}\cdot ^\circ\mathrm{C})$$

Question 10

Which of the following is a physical property?

Accepted Answer

A magnet removes iron particles from a mixture.

Question 11

What is the normal body temperature in kelvins if the normal body temperature is $$37.0\ ^\circ\mathrm{C}$$?

Accepted Answer

$$310\ \mathrm{K}$$

Question 12

How many kilojoules are released when $$50.0\ \mathrm{g} of $$steam condenses at $$100\ ^\circ\mathrm{C}$$? (Heat of vaporization for water is $$2260\ \mathrm{J/g})$$

Accepted Answer

$$Q = 50.0 	imes 2260 = 113,000\ \mathrm{J} = 113\ \mathrm{kJ}$$

Question 13

Which of the following best describes a plateau (horizontal line) on a heating curve?

Accepted Answer

A constant temperature and a change of state.

Question 14

Which process is used to prepare freeze-dried foods for long-term storage?

Accepted Answer

Sublimation

Question 15

Which of the following is an example of kinetic energy?

Accepted Answer

Rollerblading

Question 16

Which of the following statements about mixtures is correct?

Accepted Answer

Mixtures can be separated by physical methods.

Question 17

What is the temperature in degrees Celsius if the temperature is $$41.0\ ^\circ\mathrm{F}$$? (Use $$^\circ\mathrm{C} = ( ^\circ\mathrm{F} - 32 ) / 1.8)$$

Accepted Answer

$$^\circ\mathrm{C} = (41.0 - 32) / 1.8 = 5.0\ ^\circ\mathrm{C}$$

Question 18

Which of the following is a heterogeneous mixture?

Accepted Answer

Hot fudge sundae

Chapter 3: Matter and Energy – Structured Study Notes for GOB Chemistry

Guida di studio - Domande di pratica

Study guide - Flashcard