Chemistry Basics {1}

Question 1

Define:

Precision?

Answer 1

How close a series of measurements are to one another or how reproducible they are

Question 2

Define:

Systematic Error?

Answer 2

Error that tends toward being either too high or too low

Question 3

Define:

Accuracy?

Answer 3

How close the measured value is to the actual value
If the average of the attempts equal the real value then it is accurate

Question 4

Define:

Random Error?

Answer 4

Error that has equal probability of being too high or too low

Question 5

Define:

Exact Numbers?

Answer 5

Have no uncertainty and thus do not limit the number of significant figures in any calculation
Unlimited number of significant figures

Question 6

Define:

Signifcant Figures?

How many sig figs do these have?

23.5 ; 23.56 ; 0.00053 ; 5000 ; 503.405 ; 5000 ; 300.0025

Answer 6

Non-place holding digits, those that are not simply marking the decimal place
Example
23.5 -> 3 Sig Figs
23.56 -> 4 Sig Fig
0.00053 -> 2 Sig Figs
5000 -> 1 Sig Figs
503.405 -> 6 Sig Figs
505 -> 3 Sig Figs
300.002524. -> 9 Sig Figs

If decimal is present, all trailing 0s are significant
**If decimal is not present, trailing 0s in front of decimal is Ambiguous **

The greater the number of Sig Figs, the greater the certainty of measurement

Trailing Zeroes ARE SIGNIFICANT ; Leading Zeroes ARE NOT SIGNIFICANT

Question 7

Define:

Dimensional Analysis?

Answer 7

Using units as a guide to solving problems

Question 8

Define:

Conversion Factor?

Answer 8

A fractional quantity with the units we are vonverting from on the bottom and the units we are converting to on the top

Question 9

Define:

Density?

Answer 9

The substance ratio of its mass (m) to its volume (v)
M/V