Q: A serving of food contains 30 g carbohydrate (4 kcal/g), 10 g protein (4 kcal/g), and 5 g fat (9 kcal/g). What is the total caloric content?

$$30 \times 4 + 10 \times 4 + 5 \times 9 = 120 + 40 + 45 = 205\ \mathrm{kcal}$$

Q: A doctor prescribes 0.200 g of a medication. The available suspension contains 100 mg/2.0 mL. How many mL are needed for the dose?

$$0.200\ \mathrm{g} \times \frac{1000\ \mathrm{mg}}{1\ \mathrm{g}} = 200\ \mathrm{mg}$$; \frac{200\ \mathrm{mg}}{100\ \mathrm{mg}/2.0\ \mathrm{mL}} = 4.0\ \mathrm{mL}$

Q: A sample of ethanol (specific heat $$= 0.59\ \mathrm{cal/g\ ^\circ C}) $$has a mass of 20 g and is heated from $$10\ ^\circ C to$$ $$30\ ^\circ C. $$How many calories are absorbed?

$$q = m c \Delta T = 20 \times 0.59 \times (30 - 10) = 20 \times 0.59 \times 20 = 236\ \mathrm{cal}$$

Q: A value of 675 cal is equivalent to how many joules? ($$1\ \mathrm{cal} = 4.184\ \mathrm{J})$$

$$675 \times 4.184 = 2824\ \mathrm{J}$$

Q: How many calories are needed to melt 60.0 g of ice at $$0\ ^\circ C$$? (Heat of fusion for water $$= 80.\ \mathrm{cal/g})$$

$$q = m \times \text{heat of fusion} = 60.0 \times 80. = 4800\ \mathrm{cal}$$

Question 1

A patient receives a diagnostic test using a radioisotope with a half-life of 6 hours. If the initial dose is 8.0 mg, how much of the radioisotope remains after 24 hours?

Accepted Answer

$$1.0\ \mathrm{mg}$$

Question 2

Which of the following best explains why radioisotopes used in medical imaging should have short half-lives?

Accepted Answer

They minimize harmful side effects by decaying quickly.

Question 3

A serving of food contains 30 g carbohydrate (4 kcal/g), 10 g protein (4 kcal/g), and 5 g fat (9 kcal/g). What is the total caloric content?

Accepted Answer

$$30 	imes 4 + 10 	imes 4 + 5 	imes 9 = 120 + 40 + 45 = 205\ \mathrm{kcal}$$

Question 4

A metal sample has a mass of 250 g and displaces water from 40.0 mL to 65.0 mL. What is the density of the metal?

Accepted Answer

$$\frac{250\ \mathrm{g}}{65.0\ \mathrm{mL} - 40.0\ \mathrm{mL}} = \frac{250}{25.0} = 10.0\ \mathrm{g/mL}$$

Question 5

Which of the following substances will float in water (density $$= 1.00\ \mathrm{g/mL}$$)?

Accepted Answer

Balsa wood ($$D = 0.16\ \mathrm{g/mL})$$

Question 6

A doctor prescribes 0.200 g of a medication. The available suspension contains 100 mg/2.0 mL. How many mL are needed for the dose?

Accepted Answer

$$0.200\ \mathrm{g} 	imes \frac{1000\ \mathrm{mg}}{1\ \mathrm{g}} = 200\ \mathrm{mg}$$; \frac{200\ \mathrm{mg}}{100\ \mathrm{mg}/2.0\ \mathrm{mL}} = 4.0\ \mathrm{mL}$

Question 7

Which of the following is a chemical change?

Accepted Answer

Iron rusting

Question 8

What is the correct formula for aluminum sulfate?

Accepted Answer

$$\mathrm{Al}_2(\mathrm{SO}_4)_3$$

Question 9

A sample of ethanol (specific heat $$= 0.59\ \mathrm{cal/g\ ^\circ C}) $$has a mass of 20 g and is heated from $$10\ ^\circ C to$$ $$30\ ^\circ C. $$How many calories are absorbed?

Accepted Answer

$$q = m c \Delta T = 20 	imes 0.59 	imes (30 - 10) = 20 	imes 0.59 	imes 20 = 236\ \mathrm{cal}$$

Question 10

Which of the following molecules has hydrogen bonding as its main intermolecular force?

Accepted Answer

$$\mathrm{NH}_3$$

Question 11

A solution is prepared by dissolving 5 g of NaCl in 100 mL of water. What type of mixture is this?

Accepted Answer

Homogeneous mixture

Question 12

Which of the following elements has the highest ionization energy?

Accepted Answer

Chlorine ($$\mathrm{Cl})$$

Question 13

A sample of liquid nitrogen has a temperature of $$-196\ ^\circ C. $$What is this temperature in Kelvin?

Accepted Answer

$$T_K = T_{^\circ C} + 273 = -196 + 273 = 77\ \mathrm{K}$$

Question 14

Which of the following bonds is the least polar?

Accepted Answer

C-H

Question 15

What is the name of the compound $$\mathrm{FeCl}_3$$?

Accepted Answer

Iron(III) chloride

Question 16

Which of the following is a noble gas?

Accepted Answer

Argon

Question 17

A value of 675 cal is equivalent to how many joules? ($$1\ \mathrm{cal} = 4.184\ \mathrm{J})$$

Accepted Answer

$$675 	imes 4.184 = 2824\ \mathrm{J}$$

Question 18

How many calories are needed to melt 60.0 g of ice at $$0\ ^\circ C$$? (Heat of fusion for water $$= 80.\ \mathrm{cal/g})$$

Accepted Answer

$$q = m 	imes 	ext{heat of fusion} = 60.0 	imes 80. = 4800\ \mathrm{cal}$$

Question 19

Which of the following is the correct formula for the oxide ion?

Accepted Answer

$$\mathrm{O}^{2-}$$

Question 20

A patient has a temperature of $$39.0\ ^\circ C. $$What is the temperature in degrees Fahrenheit?

Accepted Answer

$$T_F = T_C 	imes \frac{9}{5} + 32 = 39.0 	imes 1.8 + 32 = 70.2 + 32 = 102.2\ ^\circ F$$

CHEM 114 Exam 1 Study Guidance

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