Q: If a sample contains 0.75 cm, how many millimeters does it contain? (Recall: $$1 \text{ cm} = 10 \text{ mm})$$

$$0.75 \times 10 = 7.5 \text{ mm}$$

Q: Which of the following is the correct way to set up a dimensional analysis problem to convert 210 inches to centimeters? ($$1 \text{ in} = 2.54 \text{ cm})$$

$$210 \text{ in} \times \frac{2.54 \text{ cm}}{1 \text{ in}}$$

Q: A student is given a measurement in yards and needs to convert it to meters. Which sequence of conversion factors would be correct if $$1 \text{ yd} = 3 \text{ ft}$$ and $$1 \text{ ft} = 0.3048 \text{ m}$$?

$$\text{yards} \times \frac{3 \text{ ft}}{1 \text{ yd}} \times \frac{0.3048 \text{ m}}{1 \text{ ft}}$$

Q: If a reaction requires 1000 grams of a substance, but your scale only measures in kilograms, what is the correct conversion to kilograms? ($$1 \text{ kg} = 1000 \text{ g})$$

$$1000 \text{ g} \times \frac{1 \text{ kg}}{1000 \text{ g}} = 1 \text{ kg}$$

Q: A patient’s medication dosage is prescribed as 5.0 mg per kg of body weight. If the patient weighs 70 kg, what is the total dosage in milligrams?

$$5.0 \text{ mg/kg} \times 70 \text{ kg} = 350 \text{ mg}$$

Q: A laboratory procedure requires you to convert 2.20 liters to milliliters. What is the correct conversion? ($$1 \text{ L} = 1000 \text{ mL})$$

$$2.20 \text{ L} \times 1000 = 2200 \text{ mL}$$

Q: A chemist needs to prepare 0.075 moles of a compound. If the molar mass is $$220 \text{ g/mol}$$, how many grams of the compound are required?

$$0.075 \text{ mol} \times 220 \text{ g/mol} = 16.5 \text{ g}$$

Q: Which of the following is the correct way to express the conversion factor for changing from seconds to hours?

$$\frac{1 \text{ hr}}{3600 \text{ s}}$$

Question 1

Which of the following best describes a conversion factor, and how is it typically used in chemical calculations?

Accepted Answer

A conversion factor is a ratio used to change units, typically written as a fraction, and is applied to cancel out unwanted units in dimensional analysis.

Question 2

A chemist needs to convert 1680 feet to meters. Given that $$1 	ext{ ft} = 0.3048 	ext{ m}$$, what is the correct calculation to find the answer?

Accepted Answer

$$1680 	imes 0.3048$$

Question 3

If a sample contains 0.75 cm, how many millimeters does it contain? (Recall: $$1 	ext{ cm} = 10 	ext{ mm})$$

Accepted Answer

$$0.75 	imes 10 = 7.5 	ext{ mm}$$

Question 4

Which of the following is the correct way to set up a dimensional analysis problem to convert 210 inches to centimeters? ($$1 	ext{ in} = 2.54 	ext{ cm})$$

Accepted Answer

$$210 	ext{ in} 	imes \frac{2.54 	ext{ cm}}{1 	ext{ in}}$$

Question 5

A student is given a measurement in yards and needs to convert it to meters. Which sequence of conversion factors would be correct if $$1 	ext{ yd} = 3 	ext{ ft}$$ and $$1 	ext{ ft} = 0.3048 	ext{ m}$$?

Accepted Answer

$$	ext{yards} 	imes \frac{3 	ext{ ft}}{1 	ext{ yd}} 	imes \frac{0.3048 	ext{ m}}{1 	ext{ ft}}$$

Question 6

If a reaction requires 1000 grams of a substance, but your scale only measures in kilograms, what is the correct conversion to kilograms? ($$1 	ext{ kg} = 1000 	ext{ g})$$

Accepted Answer

$$1000 	ext{ g} 	imes \frac{1 	ext{ kg}}{1000 	ext{ g}} = 1 	ext{ kg}$$

Question 7

A patient’s medication dosage is prescribed as 5.0 mg per kg of body weight. If the patient weighs 70 kg, what is the total dosage in milligrams?

Accepted Answer

$$5.0 	ext{ mg/kg} 	imes 70 	ext{ kg} = 350 	ext{ mg}$$

Question 8

Which of the following statements about significant figures is correct when multiplying measured values?

Accepted Answer

The result should have the same number of significant figures as the measured value with the fewest significant figures.

Question 9

A laboratory procedure requires you to convert 2.20 liters to milliliters. What is the correct conversion? ($$1 	ext{ L} = 1000 	ext{ mL})$$

Accepted Answer

$$2.20 	ext{ L} 	imes 1000 = 2200 	ext{ mL}$$

Question 10

A chemist needs to prepare 0.075 moles of a compound. If the molar mass is $$220 	ext{ g/mol}$$, how many grams of the compound are required?

Accepted Answer

$$0.075 	ext{ mol} 	imes 220 	ext{ g/mol} = 16.5 	ext{ g}$$

Question 11

Which of the following is the correct way to express the conversion factor for changing from seconds to hours?

Accepted Answer

$$\frac{1 	ext{ hr}}{3600 	ext{ s}}$$

Question 12

A solution contains 0.50 liters. How many microliters does this represent? ($$1 	ext{ L} = 1,000,000 	ext{ \mu L})$$

Accepted Answer

$$0.50 	ext{ L} 	imes 1,000,000 = 500,000 	ext{ \mu L}$$

Question 13

A car travels 100 miles. How many kilometers is this, given $$1 	ext{ mi} = 1.60934 	ext{ km}$$?

Accepted Answer

$$100 	ext{ mi} 	imes 1.60934 = 160.934 	ext{ km}$$

Question 14

Which of the following is the correct setup to convert 12 ounces to grams, given $$1 	ext{ oz} = 28.3495 	ext{ g}$$?

Accepted Answer

$$12 	ext{ oz} 	imes 28.3495 = 340.194 	ext{ g}$$

Question 15

A scientist needs to convert 5.0 kilometers to meters. What is the correct conversion? ($$1 	ext{ km} = 1000 	ext{ m})$$

Accepted Answer

$$5.0 	ext{ km} 	imes 1000 = 5000 	ext{ m}$$

Question 16

A recipe calls for 2.5 cups of flour. If $$1 	ext{ cup} = 236.588 	ext{ mL}$$, how many milliliters of flour are needed?

Accepted Answer

$$2.5 	ext{ cups} 	imes 236.588 = 591.47 	ext{ mL}$$

Question 17

A hospital orders 1.2 liters of saline solution. How many quarts is this, given $$1 	ext{ L} = 1.05669 	ext{ qt}$$?

Accepted Answer

$$1.2 	ext{ L} 	imes 1.05669 = 1.268 	ext{ qt}$$

Question 18

A student measures a distance as 222 centimeters. How many meters is this? ($$1 	ext{ m} = 100 	ext{ cm})$$

Accepted Answer

$$222 	ext{ cm} \div 100 = 2.22 	ext{ m}$$

Unit Conversions and Dimensional Analysis in General Chemistry

Study Guide - Practice Questions

Study Guide - Flashcards