Ch 2 Wks #1-Rounding and Significant FigsName______
Rules for significant figures
Non-zero digits are always significant.
Examples:657 has ______significant figures
1435 has _____ significant figures
Leading zeroes are not significant.
Examples:0.00682 has _____ significant figures
0.035 has _____ significant figures
Imbedded zeroes are always significant.
Examples:1.072 has _____ significant figures
0.0108 has _____ significant figures
Trailing zeroes are significant if there is a decimal point.
Examples:300 has _____ significant figures
300. has _____significant figures
300.0 has _____ significant figures
0.0030 has _____ significant figures
Practice: How many significant figures do the following numbers have?
A.678.0______C.0.0678______
B.6780______D6708______
Rounding –
Round 0.06507 to the indicated number of significant figures.
A.3______C.2______
B.1______
Round 8083.05 to the indicated number of significant digits.
A. 1______B. 3______C. 4______
Operations
Addition or Subtraction: The last digit retained is set by the first doubtful digit.
Examples:4.78321.0236
1.234 −0.97268
+2.02
Multiplication and Division:The answer contains no more significant figures than the least accurately known number.
Examples:2.8723 × 1.6 = ______
45.2 ÷ 6.3578 = ______
Practice:
1.How many significant figures are contained in each of the following measurements?
a.37.4 gb.6070. dm
c.0.009 03 kmd.605.03 g
e.350.0 K
2.Round off each of the following measurements to the indicated number of significant figures.
a.35.27 g to 3 significant figures
b.0.414 kL to 2 significant figures
c.87.257 dm to 3 significant figures
d.135 K to 2 significant figures
e.6250 cm to 2 significant figures
3.Round off 359.78 to the indicated number of significant figures.
a.2
b.3
c.4
d.1
4.Perform the following calculations and express the answers with the correct number of significant figures.
a.6.43 mL + 2.016 mL
b.2.50 g / 0.04 cm3
c.6.821 m + 2.0 m + 0.45 m
d.107.38 L - 65 L
e. 26.50 dm × 0.062 dm
f.1.30 g / 0.02 cm3