Language of Chemistry - Significant Figures and Rounding

Question 1

significant figures - counting

Answer 1

• 1: non-zero numbers are always significant
• 2: zeros between non-zero numbers are always significant
• 3: all trailing or final zeros to the right of the decimal are significant
• 4: placeholder zeros are not significant (use scientific notation to eliminate confusion)
• 5: counting numbers and constants are not considered in calculations as significant figures

Question 2

173.5

Answer 2

• 4 s.f.

Question 3

3.05

Answer 3

• 3 s.f.

Question 4

3.1000

Answer 4

• 5 s.f.

Question 5

0.0021

Answer 5

• 2.s.f.

Question 6

2,500,0000

Answer 6

• 2.s.f

Question 7

rounding numbers

Answer 7

• 1: if digit to right of last significant figure is less than 5, do not change last significant figure
• 2: if digit to right of last significant figure is greater than 5, increase last significant figure by one