Ch. 3 Chemistry study guide

What is the temperature of absolute zero measured in degrees C?

-273 degrees C

Chlorine boils at 239 K. What is the boiling point of chlorine expressed in degrees Celsius?

-34 degrees C

Which of the following measurements contains two significant figures?

0.000 44 L

Round off the measurement 0.003 095 5 m to three significant figures.

0.003 10 m

The quantity 44 liters expressed in cubic meters is ____.

0.044 m^3

Express 0.05 grams in kilograms, using the correct abbreviations.

0.05 g 1 kg/1000 g = 0.000 05 kg

Express 0.06 liters in cubic meters, using the correct abbreviations.

0.06 L 1 m^3/1000 L = 0.000 06 m^3

What quantity is represented by the metric system prefix deci-?

0.1

What is the density of an object having a mass of 8.0 g and a volume of 25 cm^3?

0.32 g/cm^3

What is the volume of 80.0 g of ether if the density of ether is 0.70 g/mL?

1.1 X 10^2 mL

The diameter of a carbon atom is 0.000 000 000 154 m. What is this number expressed in scientific notation?

1.54 X 10^-10 m

If the temperature changes by 100 K, by how much does it change in degrees C?

100 degrees C

What is the boiling point of water in kelvins?

373 K

The expression of 5008 km in scientific notation is ____.

5.008 X 10^3 km

What is the sum of 2.7 g and 2.47 g expressed in the correct number of significant digits?

5.2 g

Which of the following measurements is expressed to three significant figures?

7.30 10^-7 km

What is the result of multiplying 2.5 X 10^10 by 3.5 X 10^-7?

8.75 X 10^3

What is the sum of 6.210 L and 3 L expressed in the correct number of significant digits?

9 L

The following length measurements were taken by students using several different measuring devices. Find the average of the measurements. Make sure that your answer has the correct number of significant figures. 10.05 cm, 10.1 cm, 9.741 cm, 10.6 cm, 10.5 cm

Average = (10.05 + 10.1 + 9.741 + 10.6 + 10.5) / 5 = 10.2 cm

Which temperature scale has no negative temperatures?

Kelvin

If the temperature of a piece of steel decreases, what happens to its density?

The density increases.

the lowest point on the Kelvin scale

absolute zero

The closeness of a measurement to its true value is a measure of its ____.

accuracy

When a test instrument is calibrated, does its accuracy, precision, or reliability improve?

accuracy

As the density of a substance increases, the volume of a given mass of that substance ____.

decreases

What is the temperature 128 K expressed in degrees Celsius?

degrees C = K - 273 = 128 - 273 = -145 degrees C

The weight of an object ____.

depends on its location

How many significant figures are in the measurement 811.40 grams?

five

Density is found by dividing ____.

mass by volume

Conversion factors are useful in solving problems in which a given measurement must be expressed in

some other unit of measure.

When multiplying and dividing measured quantities, the number of significant figures in the result should be equal to the number of significant figures in ____.

the least precise measurement

What is the quantity 0.0075 meters expressed in centimeters?

0.75 cm

A train travels at a speed of 30 miles per hour. If 1 mile = 1.6 kilometers, how fast is the train traveling in kilometers per minute?

0.8 km/min

Which of the following equalities is correct?

1 cm^3 = 1 mL

Which of the following mass units is the largest?

1 dg

A conversion factor that shows the relationship between grams and kilograms is

1000 g/1 kg

Express the product of 2.2 mm and 5.00 mm using the correct number of significant digits.

11 mm^2

What is the measurement 111.009 mm rounded off to four significant digits?

111.0 mm

Express the sum of 7.68 m and 5.0 m using the correct number of significant digits.

12.7 m

Express the sum of 1111 km and 222 km using the correct number of significant digits.

1333 km

Which group of measurements is the most precise? (Each group of measurements is for a different object.)

2 g, 2.5 g, 3 g

What is the volume of a salt crystal measuring 2.44 X 10^-2 m by 1.4 X 10^-3 m by 8.4 X 10^-3 m?

2.9 X 10^-7 m^3

What is the result of adding 2.5 X 10^3 and 3.5 X 10^2?

2.9 X 10^3

What is the temperature -34 degrees C expressed in kelvins?

239 K

In the measurement 0.503 L, which digit is the estimated digit?

3

Express the product of 4.0 X 10^-2 m and 8.1 X 10^2 m using the correct number of significant digits.

3.2 X 10^1

Perform the following operation: 3.43 cm 5.2 cm. Make sure that your answer has the correct number of significant figures.

3.43 cm 5.2 cm = 18 cm^2

What is the product of the number 1000 and the measurement 0.003 57 m expressed in the correct number of significant digits?

3.57 m

What is the volume of 45.6 g of silver if the density of silver is 10.5 g/mL?

4.34 mL

Explain the difference between the Celsius and Kelvin temperature scales.

Both scales use the freezing point and boiling point of water as reference temperatures. The Celsius scale designates the freezing point of water as 0 degrees C and the boiling point as 100 degrees C. The region between these two points is divided into equal intervals called degrees. The Kelvin scale designates 0 K as the temperature at which the volume of an ideal gas would be zero. It is called the absolute zero because it is the lowest temperature that is theoretically attainable. Absolute zero corresponds to -273 degrees C on the Celsius scale. The Kelvin scale uses degree intervals that are the same size as the intervals on the Celsius scale. The difference between the scales lies in how the zero point is chosen. On the Celsius scale, the zero point is the freezing point of water. On the Kelvin scale, it is the point at which the volume of an ideal gas would theoretically be zero. The scales are related by the formulas: K = degrees C + 273 or degrees C = K - 273.

the non-SI scale for temperature

Celsius temperature scale

What is the density of an object having a mass of 4.0 g and a volume of 39.0 cubic centimeters?

Density = mass/volume = 4.0 g/39.0 cm^3 = 0.10 g/cm^3

You are given a jar containing a mixture of three different solid substances. The particles of each substance are larger than 0.5 cm in diameter. All you know about the substances is that each is a pure metal. Describe a method for determining the identities of the metals that make up the mixture. Assume that each metal is a different color, so you can tell one from the others.

Each substance is a pure metal, so they should be identifiable by determining their densities. Separate the solids by color into three separate batches. Determine the mass of each metal using a balance. Determine the volume of each metal as follows. Immerse each metal in a measured volume of a suitable liquid in a graduated cylinder. Measure the volume of the liquid plus the metal. Calculate the difference between the volume of the liquid plus the metal and the liquid by itself. To calculate the density, divide the mass of each metal by its volume. Compare the density and color of each metal to the density and color listed in reference books.

the SI scale for temperature

Kelvin temperature scale

The density of osmium, which is the densest metal, is 22.57 g/cm^3. What is the mass of a block of osmium that measures 1.00 cm 4.00 cm 2.50 cm?

Mass = density volume = 22.57 g/cm^3 X 1.00 cm X 4.00 cm X 2.50 cm = 226 g

Explain the difference between mass and weight. Provide an example to illustrate the distinction.

Mass is a measure of the quantity of matter in an object. Weight is a measure of the strength of the pull of a gravitational force (usually Earth's) on an object. The weight of an object changes, however, with the object's distance from the center of the gravitational field it is in. The mass of a person is exactly the same whether the person is on Earth or on the moon. The weight of that person will be much less on the moon than on Earth because the gravitational pull of the moon is much less than that of Earth.

The density of mercury is 5,427 kg/(m3). If the density of water is 1.0 g/mL, will mercury float or sink in water?

Mercury will sink because the density of mercury is 5.427 g/mL, which is greater than the 1.0 g/mL density of water.

Why is the density of a metal greater than the density of water?

Metal's density is greater because the metal's atoms are heavier than the water molecules. Another explanation is that it is more dense because the metal atoms are more closely packed than the water molecules.

A cube of a gold-colored metal with a volume of 59 cm^3 has a mass of 980 g. The density of pure gold is 19.3 g/cm^3. Is the metal pure gold? Show calculations to justify your answer.

No; mass/volume = 980 g/59 cm^3 = 17 g/cm^3

Explain the difference between precision and accuracy. Suppose you made three different mass measurements of a sugar sample you knew to have a mass of 1 g. How would you know whether or not the measurements were accurate? How would you know whether or not they were precise? Could the three measurements be precise, but not accurate? Explain.

Precision is the reproducibility of a measurement made under the same conditions; accuracy is the closeness of a measurement to the true value of the measurement. The three measurements would be precise if they were very close to each other in value; they would be accurate if they were close to the actual 1-g mass of the sample. If the measurements are very close to each other, they are precise, regardless of how close they are to the real value. Therefore, the measurements could be precise, but not accurate.

Describe the rules that are used to determine the number of significant figures in the results of addition, subtraction, multiplication, and division.

The answer of an addition or subtraction can have no more digits to the right of the decimal point than are contained in the measurement with the least number of digits to the right of the decimal point. The answer of a multiplication or division can have no more significant figures than the measurement having the least number of significant figures. For multiplication and division, the position of the decimal point has nothing to do with the number of significant figures.

Why is the metric system the preferred system of measurement for science?

The metric system is important because of its simplicity and ease of use. The metric system is preferred for science because it is based on units that are multiples of ten, thus simplifying conversions between units. In addition, all necessary units can be derived from the seven basic units of the metric system.

Why do the densities of most substances decrease with temperature?

The student should infer that this is because a substance's atoms or molecules tend to move farther apart with an increase in temperature. Consequently, the volume of the substance increases. There is no change in the mass of the substance, however, and therefore the density (mass/volume) decreases.

If a liter of water is heated from 20 degrees C to 50 degrees C, what happens to its volume?

The volume increases.

What is the volume of an object with a density of 7.73 g/cm^3 and a mass of 5.40 X 10^2 g?

Volume = mass / density = (5.40 X 10^2 g) / 7.73 g/cm^3 = 69.9 cm^3

closeness to true value

accuracy

When a measurement is multiplied by a conversion factor, the numerical value

is generally changed, but the actual size of the quantity measured remains the same.

The chief advantage of the metric system over other systems of measurement is that it ____.

is in multiples of 10

What is the SI unit of mass?

kilogram

Which of the following units is NOT an official SI unit?

liter

kilogram is the SI base unit for this quantity

mass

What is the metric system prefix for the quantity 0.000 001?

micro-

Which of the following volumes is the smallest?

one microliter

The mass of the electron is 9.109 39 X 10^-31 kg. Express the mass of the electron to 1, 2, 3, and 4 significant figures.

one: 9 X 10^-31 kg; two: 9.1 X 10^-31 kg; three: 9.11 X 10^-31 kg; four: 9.109 X 10^-31 kg

Three different people weigh a standard mass of 2.00 g on the same balance. Each person obtains a reading of 7.32 g for the mass of the standard. These results imply that the balance that was used is ____.

precise

narrowness of range of measurements

precision

known or estimated in a measurement

significant figure

How many significant figures are in the measurement 0.003 4 kg?

two

A cubic meter is about the same as the volume occupied by a ____.

washing machine

the force of gravity on an object

weight