Exercise 1A

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Solutions, hints and answers can be found in the Solutions Page. It is strongly recommended that students do not look at the solutions until after completing or attempting to complete the problems. Going straight to the solutions will reduce the point of the exercises.

1.1

Calculate the result of each of the following and record answer with the proper number of significant figures.

13.4 + 9.8 + 55.99
340.5 * 419.23
19.45 / 14.23
7 - 2.8

1.2

Calculate and express the result in the correct number of significant figures.

(1.602 x 10^-¹⁹) x (2.15 x 10³)
(3.1667 x 10²³) x (9.018 x 10^-9) / (7.52 x 10⁴)
1.714 x 10^-1+ 1.96 x 10^-3 + 1.255 x 10^-2
(7.00743 - 7.00521) / (5.9831 x 10¹⁹ )
(4.832 x 10^-5 - 4.760 x 10^-5) / (4.832 x 10^-5) x 100 (100 is exact)
(9.02 x 10³ + 8.99 x 10³+ 1.065 x 10⁴) / 3 (3 is exact)

1.3

Convert the following temperatures to Kelvin and Fahrenheit degrees.

room temperature: 20.0 ^oC
the boiling point of water: 100.^oC
the temperature of human: 37.0 ^oC

1.4

Using the following table, calculate the volume of 50.0 g of each of the following substances at 20.0^o C. What does the volume of oxygen gas tell you about the properties of gasses?

Substance	Physical State	Density (g/cm³)
Ethanol	Liquid	0.789
Iron	Solid	7.87
Oxygen	Gas	0.00133

Oxygen gas
Iron
Ethanol

1.5

A student gets three thermometers from the lab. He notices that these thermometers use different units for measurements. They are ^oF, ^oC, and K. If he puts these thermometers into three water baths and observe a 10 degree change for each thermometer, which water bath has the smallest change in temperature ?

1.6

What is the main difference between each of the following pairs?

An elemental substance (element) and a compound
Physical and chemical changes
Homogeneous and heterogeneous mixtures

1.7

Define whether each of the following is a pure substance or a mixture.

salad dressing
copper
bronze
silk
ice
sand
magnesium
solid potassium iodide (KI)
honey

1.8

Are these chemical or physical changes?

A nail rusting.
Toast burning.
Water boiling.
Ice cream melting.

1.9

The actual amount of magnesium in a sample is 21.14%. A student analyzed the magnesium in the sample and obtained the results: 20.36%, 20.37%, 20.34%, 20.37%. Explain the accuracy and precision of these results.