Chapter 1: Significant Figures and Unit Conversions

Question 1

Significant Figures

Answer 1

includes all digits known with certainty plus one digit that is uncertain

Question 2

Significant Figures

Answer 2

includes all digits known with certainty plus one digit that is uncertain; all nonzero digits are significant

Question 3

Significant Figures: Zero Rules

Answer 3

leading zeros/only zeros on the left side of integers are NOT SIGNIFICANT;
(0.0392 has 3 s.f.)

trailing zeros are not signifcant unless they come after a decimal point; (3700 has 2 s.f.)

captive zeros are ALWAYS signifcant;
(16.07 has 4 s.f.)

Question 4

Rounding significant figures

Answer 4

1.) if the number is followed by a number less than 5, the digit remains unchanged

2.) if the number being rounded is followed by a number greater than 5, the digit will increase by 1

3.) if the digit removed is 5, the preceding number increases by 1 if it is odd and remains unchanged if it is even
(17.75–17.8, 17.65—17.6)

4.) if the number 5 is followed by zeros, follow above 3rd rule; if followed by nonzeros, rule 2 is followed
(17.6500—17.6, 17.6513—-17.7)

Question 5

Significant Figures in Mathematical operations

Answer 5

Rounding off: Drop “insignificant” digits; Only at the end of calculations!!!

“Weakest link” principle: The number of significant figures in the final result cannot be
greater than the “weakest link” used in the calculation; The actual rule depends on the mathematical operation

Question 6

Multiplication and Division Rule of Significant Figures in Calculations

Answer 6

The answer contains the same number
of significant figures as there are in the measurement with the fewest significant figures.

Question 7

Addition and Subtraction rule of significant figures in calculations

Answer 7

The answer has the same number of
decimal places as there are in the measurement with the fewest decimal
places.

Question 8

Significant figure rules for calculations that have multiple steps

Answer 8

To determine the number of significant figures, we must first perform individual operations to determine the number of significant figures at each step

Ex. (1.23g - 0.567g)/ 0.34442cm^3 = ?

• perform the subtraction first separately to give 2 s.f, then divide and end with 2 s. f.

Question 9

Conversion Factor

Answer 9

a fraction that represents the relationship between two quantities; derived from equalities

starting quanity x conversion factor = equivalent quantity