Q: A chemist needs to convert 250 mL of a solution to liters. Which conversion factor should be used?

$\frac{1 \text{ L}}{1000 \text{ mL}}$

Q: Which of the following is the correct setup for converting 80 mg of a substance to grams using dimensional analysis?

$80 \text{ mg} \times \frac{1 \text{ g}}{1000 \text{ mg}}$

Q: What is the average rate of increase in atmospheric CO$_2$ concentration between 1960 (317 ppm) and 2010 (389 ppm)?

$\frac{389 - 317}{2010 - 1960} = 1.44 \text{ ppm/year}$

Q: If the average rate of increase in CO$_2$ concentration from 1960 to 2010 is $1.44 \text{ ppm/year}$, estimate the concentration in 2050.

$389 + (1.44 \times 40) = 446.6 \text{ ppm}$

Q: A solution contains 0.80 mL of acetaminophen suspension with a concentration of 80 mg/mL. How many milligrams of acetaminophen are present?

$0.80 \text{ mL} \times 80 \text{ mg/mL} = 64 \text{ mg}$

Q: Which equation correctly represents the general format for dimensional analysis as shown in the study materials?

$\text{Given unit} \times \frac{\text{Desired unit}}{\text{Given unit}}$

Q: A student wants to convert 5.0 kg to pounds. Which conversion factor should be used?

$\frac{2.205 \text{ lbs}}{1 \text{ kg}}$

Question 1

Which of the following best describes the purpose of dimensional analysis in chemistry problem solving?

Accepted Answer

To convert between different units using conversion factors.

Question 2

A chemist needs to convert 250 mL of a solution to liters. Which conversion factor should be used?

Accepted Answer

$\frac{1 	ext{ L}}{1000 	ext{ mL}}$

Question 3

A 747 jet is fueled with 173,231 liters of jet fuel. If the density of the fuel is $0.768 	ext{ g/mL}$, what is the mass of the fuel in kilograms?

Accepted Answer

$1.33 	imes 10^5 	ext{ kg}$

Question 4

Which of the following is the correct setup for converting 80 mg of a substance to grams using dimensional analysis?

Accepted Answer

$80 	ext{ mg} 	imes \frac{1 	ext{ g}}{1000 	ext{ mg}}$

Question 5

An infant weighing 22 lbs needs a dose of acetaminophen suspension (80 mg/mL). The recommended dose is 15 mg/kg. How many mL should be given? (1 kg = 2.205 lbs)

Accepted Answer

$0.95 	ext{ mL}$

Question 6

What is the average rate of increase in atmospheric CO$_2$ concentration between 1960 (317 ppm) and 2010 (389 ppm)?

Accepted Answer

$\frac{389 - 317}{2010 - 1960} = 1.44 	ext{ ppm/year}$

Question 7

If the average rate of increase in CO$_2$ concentration from 1960 to 2010 is $1.44 	ext{ ppm/year}$, estimate the concentration in 2050.

Accepted Answer

$389 + (1.44 	imes 40) = 446.6 	ext{ ppm}$

Question 8

Which of the following is NOT a step in the problem solving strategy outlined in the study materials?

Accepted Answer

Guessing the answer based on intuition.

Question 9

A solution contains 0.80 mL of acetaminophen suspension with a concentration of 80 mg/mL. How many milligrams of acetaminophen are present?

Accepted Answer

$0.80 	ext{ mL} 	imes 80 	ext{ mg/mL} = 64 	ext{ mg}$

Question 10

Which equation correctly represents the general format for dimensional analysis as shown in the study materials?

Accepted Answer

$	ext{Given unit} 	imes \frac{	ext{Desired unit}}{	ext{Given unit}}$

Question 11

A student wants to convert 5.0 kg to pounds. Which conversion factor should be used?

Accepted Answer

$\frac{2.205 	ext{ lbs}}{1 	ext{ kg}}$

Question 12

Which real-world scenario best illustrates the importance of calculating mass using density and volume?

Accepted Answer

Determining the amount of jet fuel needed for a flight.

Question 13

If a chemist has 1000 mL of a liquid with a density of $1.25 	ext{ g/mL}$, what is the mass in kilograms?

Accepted Answer

$1.25 	ext{ g/mL} 	imes 1000 	ext{ mL} = 1250 	ext{ g} = 1.25 	ext{ kg}$

Question 14

Which of the following is a common mistake when using conversion factors in dimensional analysis?

Accepted Answer

Placing the conversion factor upside down, resulting in incorrect unit cancellation.

Question 15

A scientist measures a sample as 0.50 L. How many mL is this?

Accepted Answer

$0.50 	ext{ L} 	imes 1000 	ext{ mL/L} = 500 	ext{ mL}$

Question 16

Why is it important to identify both the starting point and the end point in a chemistry problem?

Accepted Answer

It helps to organize the steps needed to reach the solution.

Question 17

A solution contains 15 mg of a drug per kg of body weight. If a patient weighs 70 kg, how many mg should be administered?

Accepted Answer

$15 	ext{ mg/kg} 	imes 70 	ext{ kg} = 1050 	ext{ mg}$

Question 18

Which of the following best explains why conversion factors are written as fractions?

Accepted Answer

To allow units to cancel appropriately during multiplication.

Matter, Measurement, and Problem Solving (Ch. 1.8–1.9): Dimensional Analysis and Chemical Problem Solving

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