Numbers in Chemistry

Question 1

What is an analog measuring device?

Answer 1

A device in which there is a scale that must be interpreted; it is not digital.

Question 2

What is the uncertainty for an analog device?

Answer 2

Plus or minus one-half the smallest increment.

Question 3

What is the uncertainty for a digital device?

Answer 3

Plus or minus the smallest decimal place.

Question 4

A digital scale reads 50.67 g. What is the uncertainty? What does this mean about the measurement?

Answer 4

Uncertainty= plus or minus 0.01 g. This means that the actual measurement is somewhere between 50.66 g and 50.68 g.

Question 5

It is important to use significant figures to…

Answer 5

Report measurements to reflect the accuracy of the equipment used.

Question 6

Which digits are always significant?

Answer 6

1-9.

Question 7

Zeros between significant figures are…

Answer 7

Significant. (Ex. 5,007 has 4 sig figs.)

Question 8

When are trailing zeros in a number significant?

Answer 8

Trailing zeros are significant only if the number has a decimal point. Ex: 100.00 has 5 sig figs, but 100 has 1 sig fig.

Question 9

Zeros in the beginning of a number whose only function is to place the decimal point are…

Answer 9

Not significant. Ex: 0.0025 has 2 sig figs.

Question 10

Zeros following a decimal significant figure are…

Answer 10

Significant. Ex: 0.4700 has 4 sig figs.

Question 11

How do you use sig figs when multiplying or dividing?

Answer 11

Round your final answer to the least number of sig figs. Ex: 1.5 x 5= 7.5, but since 5 has only 1 sig fig, we round the final answer to 8.

Question 12

How do you add or subtract with sig figs?

Answer 12

Round your final answer to the least accurate decimal place.

Question 13

What is percent error?

Answer 13

A way for scientistst to express how far off a laboratory value is from the commonly accepted value.

Question 14

How do you calculate percent error?

Answer 14

Find the absolute value of this: (Accepted value-experimental value) / accepted value. Then multiply that by 100.

Question 15

The Metric System is also known as…

Answer 15

The International System of Units or S.I.

Question 16

The metric system was developed in this country:

And this year:

Answer 16

France, 1790

Question 17

The metric system is a base___system.

Answer 17

Base 10 system.

Question 18

Mass is measured in…

Answer 18

Grams. g.

Question 19

Volume is measured in…

Answer 19

Liters. L.

Question 20

Distance is measured in…

Answer 20

Meters. m.

Question 21

Time is measured in…

Answer 21

Seconds. s.

Question 22

Temperature is measured in…

Answer 22

Degrees Celsius or Kelvin. C or K.

Question 23

Substance quantity is measured in…

Answer 23

Moles. mol.

Question 24

1 mL is equivalent to what other measurement of volume?

Answer 24

1 mL=1 cm^3 (cc)

Question 25

List the prefixes from least to greatest.

Answer 25

Micro, milli, centi, deci, deca, hecto, kilo, Mega, Giga

Question 26

The symbol and value for micro

Answer 26

Fancy m, 1 x 10^-6

Question 27

Symbol and value for milli

Answer 27

m, 1 x 10^-3

Question 28

Symbol and value for centi

Answer 28

c, 1 x 10^-2

Question 29

Symbol and value for deci

Answer 29

d, 1 x 10^-1

Question 30

Symbol and value for deca

Answer 30

da, 1 x 10^1

Question 31

Symbol and value for hecto

Answer 31

h, 1 x 10^2

Question 32

Symbol and value for kilo

Answer 32

k, 1 x 10^3

Question 33

Symbol and value for Mega

Answer 33

M, 1 x 10^6

Question 34

Symbol and value for Giga

Answer 34

G, 1 x 10^9

Question 35

Formula for velocity

Answer 35

Velocity=distance/time

Question 36

Formula for density

Answer 36

Density=mass/volume

Question 37

Formula for pressure

Answer 37

Pressure=force/area

Question 38

Velocity is measured as...

Answer 38

m/s or meters per second

Question 39

Density is measured as...

Answer 39

g/mL or grams per milliliter

Question 40

Pressure is measured as...(metric)

Answer 40

N/m^2 or Newtons per square meter

Question 41

How does the English System measure pressure?

Answer 41

psi or lb/in^2 (pounds per square inch)

Question 42

When you put numbers is scientific notation, make sure to always include...

Answer 42

Significant zeros.

Question 43

What is dimensional analysis?

Answer 43

Using unit conversion factors/ratios to solve quantitative problems.

Question 44

What are derived units?

Answer 44

Units that come from a calculated value.

Question 45

Density is an ___ ____property.

Answer 45

Intrinsic physical property.

Question 46

Formula for density

Answer 46

Mass/volume

Question 47

Formula for mass

Answer 47

Density * volume

Question 48

Formula for volume

Answer 48

Mass/density

Question 49

Interpret this: 78,000 +- 1 in scientific notation

Answer 49

The plus/minus one means keep it accurate to the ones place. So in scientific notation, it would be 7.8000 x 10^4.