Q: Which of the following is the correct value for Avogadro's number, $$N_A$$, as given in the provided materials?

$$6.022 \times 10$$^{23}$$\ \text{mol}^{-1}$$

Q: A student needs to convert $$15\ \text{km} to $$meters. Which of the following is the correct conversion factor and answer?

Multiply by $$1000$$; $$15\ \text{km} \times 1000 = 15,000\ \text{m}$$

Q: If you have $$100.0\ \text{mol} of Fe$$, how many atoms of Fe do you have? (Use $$N_A = 6.022 \times 10$$^{23}$$\ \text{mol}^{-1})$$

$$100.0 \times 6.022 \times 10$$^{23}$$ = 6.022 \times 10$$^{25}$$ atoms

Q: Convert $$2.80 \times 10^5$\ \mu\text{L} to mL.$$

$$2.80 \times 10^2$\ \text{mL}$$

Q: Which of the following correctly converts $$20\ \text{m/s} to$$ $$\text{km/hr}$$?

$$20\ \text{m/s} \times \frac{1\ \text{km}}{1000\ \text{m}} \times \frac{3600\ \text{s}}{1\ \text{hr}} = 72\ \text{km/hr}$$

Q: Which of the following is the correct conversion for $$1\ \text{in} = 2.54\ \text{cm}$$?

$$1\ \text{in} = 2.54\ \text{cm}$$

Q: Which of the following is the correct way to express $$0.000232\ \text{L} in $$scientific notation?

$$2.32 \times 10$$^{-4}$$\ \text{L}$$

Q: A student is asked to convert $$15\ \text{km} to $$miles. Which conversion factor should they use?

$$1\ \text{mi} = 1.609\ \text{km}$$

Question 1

Which of the following is the correct value for Avogadro's number, $$N_A$$, as given in the provided materials?

Accepted Answer

$$6.022 	imes 10$$^{23}$$\ 	ext{mol}^{-1}$$

Question 2

A student needs to convert $$15\ 	ext{km} to $$meters. Which of the following is the correct conversion factor and answer?

Accepted Answer

Multiply by $$1000$$; $$15\ 	ext{km} 	imes 1000 = 15,000\ 	ext{m}$$

Question 3

If you have $$100.0\ 	ext{mol} of Fe$$, how many atoms of Fe do you have? (Use $$N_A = 6.022 	imes 10$$^{23}$$\ 	ext{mol}^{-1})$$

Accepted Answer

$$100.0 	imes 6.022 	imes 10$$^{23}$$ = 6.022 	imes 10$$^{25}$$ atoms

Question 4

Convert $$2.80 	imes 10^5$\ \mu	ext{L} to mL.$$

Accepted Answer

$$2.80 	imes 10^2$\ 	ext{mL}$$

Question 5

A car is traveling at $$42\ 	ext{miles/hr}. $$What is this speed in $$	ext{miles/min}$$?

Accepted Answer

$$0.70\ 	ext{miles/min}$$

Question 6

Convert $$232\ 	ext{cm}^3 to $$liters.

Accepted Answer

$$0.232\ 	ext{L}$$

Question 7

A solution has a concentration of $$15\ 	ext{mol/L} of$$ $$	ext{C}_6	ext{H}_{12}	ext{O}_7. $$How many moles are present in $$2.0\ 	ext{L} of $$this solution?

Accepted Answer

$$30\ 	ext{mol}$$

Question 8

The distance from McAllister Hall to Memorial Library is $$0.50\ 	ext{km}. If $$the average walking speed is $$3.0\ 	ext{miles/hr}$$, how many minutes will it take to walk from the library to the chemistry building? (Use $$1\ 	ext{mi} = 1.609\ 	ext{km})$$

Accepted Answer

$$6.4\ 	ext{minutes}$$

Question 9

Which of the following correctly converts $$20\ 	ext{m/s} to$$ $$	ext{km/hr}$$?

Accepted Answer

$$20\ 	ext{m/s} 	imes \frac{1\ 	ext{km}}{1000\ 	ext{m}} 	imes \frac{3600\ 	ext{s}}{1\ 	ext{hr}} = 72\ 	ext{km/hr}$$

Question 10

Which of the following is the correct conversion for $$1\ 	ext{in} = 2.54\ 	ext{cm}$$?

Accepted Answer

$$1\ 	ext{in} = 2.54\ 	ext{cm}$$

Question 11

A chemist needs to convert $$102\ 	ext{mmol} to $$mol. What is the correct answer?

Accepted Answer

$$0.102\ 	ext{mol}$$

Question 12

Which of the following best describes the process of dimensional analysis in chemistry?

Accepted Answer

A method of converting units by multiplying by conversion factors so that units cancel appropriately.

Question 13

If a student incorrectly uses $$1\ 	ext{mi} = 2.54\ 	ext{km}$$ instead of $$1\ 	ext{mi} = 1.609\ 	ext{km}$$, what will be the effect on their answer when converting miles to kilometers?

Accepted Answer

Their answer will be too large.

Question 14

A laboratory procedure requires $$0.500\ 	ext{L} of a $$solution. If you only have a $$250\ 	ext{mL}$$ graduated cylinder, how many full cylinders do you need to measure out the required volume?

Accepted Answer

2

Question 15

Which of the following is the correct way to express $$0.000232\ 	ext{L} in $$scientific notation?

Accepted Answer

$$2.32 	imes 10$$^{-4}$$\ 	ext{L}$$

Question 16

A student is asked to convert $$15\ 	ext{km} to $$miles. Which conversion factor should they use?

Accepted Answer

$$1\ 	ext{mi} = 1.609\ 	ext{km}$$

Unit Conversions and Dimensional Analysis in General Chemistry

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