Chapter 2: Measurement and Problem Solving

Question 1

Describe what a measurement is.

Answer 1

In chemistry, measurement is described as a quantity. Is an amount of something that has a number and a unit.

Question 2

Remember a measurement is a number and its unit.

Question 3

Explain how to use scientific notation to express numbers. Be able to convert between decimal form (standard notation) and scientific notation

Answer 3

Scientific Notation is used when there are really small or really big numbers. A base number that is bigger an 1 but smaller than 10, multiplied by a power of 10^n

Question 4

Explain how to add, subtract, multiply and divide numbers expressed in scientific notation. Be able to use your calculator to obtain the correct results from these math
operations.

Answer 4

When adding and subtracting numbers expressed in scientific notation, the power must be the same, therefore be converted if they are different. When multiplying and dividing numbers expressed in scientific notation, the power is either added or subtracted (based on the operation), and the bases are multiplied or divided (based on the operation)

Question 5

Clearly distinguish between the terms accuracy and precision used to describe the quality of measurements

Answer 5

Accuracy is how close the measured value is to the true value, based on the tool. Precision is how repeatable the measurement is, based on the user of the tool.

Question 6

Explain the meaning of uncertainty in measurements.

Answer 6

There is always some uncertainty in measurement. Some tools are more certain than others. A cylinder that measures by 5 milliliters has more uncertainty than a cylinder that is measure by milliliters.

Question 7

Describe the difference between the certain numbers in a measurement and the uncertain number in a measurement.

Answer 7

The number closest to the right is an UNCERTAIN number all other numbers to the left are CERTAIN numbers

Question 8

Explain the difference between an exact number and a number with significant figures.

Answer 8

Exact numbers are counting numbers (ex: 1,2,3…) Significant Figures has certain digits and one uncertain number.

Question 9

Remember the guidelines for determining the number of significant figures (also known as sig figs or significant digits) associated with any measurement

Answer 9

Sig Figs are all numbers that are not zeros unless there are zeros between numbers (ex:1208)

Question 10

Explain how to determine the number of digits to report in an answer when measurements are added or subtracted.

Answer 10

When adding or subtracting, limit the number of sig figs to how many are shared.

Question 11

Explain how to determine the number of digits to report in an answer when measurements are multiplied or divided.

Answer 11

When multiplying, numbers are recorded with how many sig figs the number with the lowest count of sig figs

Question 12

Remember the guidelines used to round off to the correct number of significant figures.

Answer 12

If the number that is being rounded is 5 or higher, it us rounded up. If its smaller than 5 its rouned down

Question 13

Remember the SI unit and its symbol for mass, length, time, temperature and volume.

Answer 13

Mass: grams (g). Length: meters (m). Time: seconds (s). Temperature: Celsius (C), kelvin (K). volume: liters (L)

Question 14

mega

Answer 14

10^6 of the base

Question 15

kilo-

Answer 15

10^3 of the base
(k)

Question 16

hecto-

Answer 16

10^2 of the base
(h)

Question 17

deci-

Answer 17

10^1 of the base
(d)

Question 18

centi-

Answer 18

10^-2 of the base
(c)

Question 19

mili-

Answer 19

10^-3 of the base
(m)

Question 20

micro-

Answer 20

10^-6 of the base
(µ)

Question 21

nano-

Answer 21

10^-9 of the base
(n)

Question 22

A unit conversion factor is a ratio of two equivalent quantities. For example, we know that 1000 g = 1 kg. This ratio is written as. The reciprocal of a unit conversion factor is an equivalent unit conversion factor. For example, remember that a conversion factor written as 1000 g/1 kg must be written as before it can be used in a calculation!

Question 23

Define density.

Answer 23

mass divided by volume