Chem Lab Exam 1 - Measurements In Chemistry

Front 1

How many sigfigs:
1.2

Back 1

2

Front 2

How many sigfigs:
8117

Back 2

4

Front 3

How many sigfigs:
4.08

Back 3

3

Front 4

How many sigfigs:
30002

Back 4

5

Front 5

How many sigfigs:
3.6050

Back 5

5

Front 6

How many sigfigs:
490.

Back 6

3

Front 7

How many sigfigs:
1.20 x 10^3

Back 7

3

Front 8

How many sigfigs:
3 x 10^2

Back 8

1

Front 9

How many sigfigs:
0.067

Back 9

2

Front 10

How many sigfigs:
0.0009

Back 10

1

Front 11

How many sigfigs:
12000

Back 11

2

Front 12

How many sigfigs:

3000

Back 12

1

Front 13

Nonzero digits are/are not significant

Back 13

are

Front 14

Zeroes at the beginning of a number are/are not significant

Back 14

are not

Front 15

All digits in a properly written number in scientific notation are/are not significant

Back 15

are

Front 16

Zeroes at the end of a number including a decimal are/are not significant

Back 16

are

Front 17

Zeroes at the end of a number without a decimal are/are not significant

Back 17

are not

Front 18

How many sigfigs:
1.2000 x 10^4

Back 18

5

Front 19

For ______ and ______, the answer must have the same number of decimal places as the term with the smallest number of decimal places.

Back 19

addition; subtraction

Front 20

For ________ or _______, the result must have the same number of sigfigs as the term with the least number of significant figures

Back 20

multiplication

Front 21

1.003+13.45+0.0057+14.4587=

Answer with the correct number of sig figs or decimal places

Back 21

14.46

Front 22

(15.03)(4.87)/1.987=

Answer with the correct number of sig figs or decimal places

Back 22

36.8

Front 23

Name four instruments used to measure temperature. Which do we use most often in lab?

Back 23

Mercury thermometers, alcohol thermometers, thermocouple-based thermometers, and infrared thermometers; we use alcohol thermometers most often

Front 24

When recording values using instruments to measure temperature, it is important to read and record to ONE more decimal place than the markings on the device indicate, T/F?

Back 24

T

Front 25

The derived value which indicates the amount of space taken up by a sample.

Back 25

Volume

Front 26

Graduated cylinders, pipets, burets, volumetric flasks, and syringes are all examples of instruments used to measure ______.

Back 26

Volume

Front 27

When accuracy is the most important criterion for your choice while measuring volume, which two instruments would be the best?

Back 27

pipets, volumetric flasks.

Front 28

When reading the markings on a measuring device, an incorrect eye position can make the amount seem higher or lower than the true value. What is the phenomenon called?

Back 28

Parallax

Front 29

Do you read the meniscus at the bottom or top?

Back 29

Bottom

Front 30

Experimental errors can be classified as either ______ or ______.

Back 30

systematic; random

Front 31

________ errors can arise if we use broken or uncalibrated equipment or if we use the wrong experimental design and techniques. It is possible to remove this error completely.

Back 31

systematic

Front 32

_______ errors arise from uncontrolled variables in the measurement such as the fluctuation in temperature, pressure, electrical noise, ect. Different people may report results for the same scale.This kind of error has an equal chance of being positive or negative. This type of error is always present and cannot be eliminated.

Back 32

Random

Front 33

T/F: Random error is always present and cannot be eliminated.

Back 33

T

Front 34

We can make conclusions about our results with complete certainty, T/F? Why?

Back 34

F, because random errors are always present

Front 35

_______ describes how close a measured value is to the "true" value. _______ describes the reproducibility of the results.

Back 35

Accuracy; precision

Front 36

The closer the measured value is to the true value, the more accurate/precise it is.

Back 36

accurate

Front 37

If we repeat the measurements several times and receive the values that are very close to eachother, then our measurements are?

Back 37

precise

Front 38

Measurements that are close to the"true" value and close to each other are considered?

Back 38

Both accurate and precise

Front 39

If the measurements are close to the true value, but not to each other, and the results are?

Back 39

Accurate, but not precise

Front 40

If the data points are not close to the true value, but are close to each other, then the data is?

Back 40

Not accurate, but precise

Front 41

If the measurements are neither close to the correct or"true" value nor to each other, they are?

Back 41

Neither accurate nor precise

Front 42

_______ properties depend on the amount (extent) of material involved, whereas _______ properties do NOT depend on the amount of material present.

Back 42

Extensive; intensive

Front 43

Density is intensive/ extensive?

Back 43

Intensive

Front 44

An intensive property defined as mass per unit volume (mass/volume).

Back 44

Density

Front 45

Mass and volume are extensive/Intensive properties?

Back 45

Extensive

Front 46

For most solids and liquids, the mass is measured in ________. Volume is measured either in ________ or in ________, resulting in density having units that either _____ or _____.

Back 46

Grands; cubic centimeters, milliliters; g/cm^3, g/mL

Front 47

The _____ of a solid can be determined directly only if the solid has a regular geometry (e.g. A regular column, a cube, a cylinder, a rectangle or solid or a sphere) by simply measuring dimensions and using a formula.

Back 47

Volume

Front 48

The volume of the solid can determined directly only if?

Back 48

The solid has a regular geometry

Front 49

How do you find volume of an irregular solid?

Back 49

Measure the volume displaced by the solid when submerged in liquid (water displacement).

Front 50

The standard deviation is a statistical measurement of the _______ in the measurement of value. The % error indicates how much ________ is present in the measurement of a value relative to its magnitude.

Back 50

Imprecision; inaccuracy

Front 51

You are given a rectanglular block and told to find its density. Explain the procedure.

Back 51

First, I know D=M/V. I would weigh the rectangular block on a top loading balance and record the mass in grams. I would then use a ruler to measure the length, width, and height of the block in centimeters, using the formula V=lxwxh. Then, I would use those two findings to solve for density.

Front 52

You are given an irregularly shaped solid substance and told to find its density. Explain the procedure.

Back 52

First, I know D=m/v. I would substance way to substance on night a top loading balance and record the mass in grams. I would then obtain a graduated cylinder, fill it partially with water, and record the initial volume of the water. Then, I would place the substance into the cylinder and remeasure the volume of the water. I would subtract the second measurement from the initial volume to find the volume of the irregular substance. Lastly, I would use the mass measurement and the final volume to solve for density.

Front 53

You are given an assigned 10 mL of liquid and asked to find the density. Explain the procedure.

Back 53

First, I know D=m/v. I would first obtain a flask or beaker, weigh it on a top loading balance, and record the mass in grams. I would then add the liquid to the flask, and reweigh. Finally, I would calculate the mass of the liquid by taking these two measurements and finding the difference. mass of liquid= mass of flask and liquid - mass of flask. To find the density, I would divide the mass by the volume of the liquid, 10 mL.

Front 54

You are given a top loading balance, a clean, dry 100 mL beaker, and are told to fill it with water to the 80 mL mark. Assuming that the temperature is 23°C (where the density of water is 0.998203 g/mL. Calculate the volume contained in the beaker.

Back 54

First, I know D=m/v. I would first weigh to beaker by itself, and then the beaker containing the 80 mL of water. I would subtract these numbers to find the mass in grams. Now that I know the mass and the density of the water, I can rearrange the equation to solve for volume: V=M/D in mL.

Front 55

For multiple measurements, for which you must calculate an average and a standard deviation, you will round your calculated standard deviation to how many digits? What will you round the average to?

Back 55

One digit; round the average to the same number of placeholders as your standard deviation

Front 56

How many sigfigs:
0.002060

Back 56

4; zero's at the beginning of a number are not significant, regardless of whether there is a decimal or not.

Front 57

You were given a block, and calculated the density to be 2.28 g/mL. You were given the density of water at 0.9982 g/mL. Given this information, would the block float or sink in water?

Back 57

Since the density of water is much less than the density of the block, the block with sink.

Front 58

You are told to measure the volume of 80 mL of water, and are given the option of choosing a graduated cylinder or 100 mL beaker. Which accuracy being important, which should you choose?

Back 58

Graduated cylinder