Significant Figures (Sigfigs)
SigFig Rules:
All non-zero digits are significant (211.8 has four sigfigs).
Zeros between non-zero digits are significant (20007 has five sigfigs).
Leading zeros in a number are not significant (0.0085 has two sigfigs).
Trailing zeros are not significant unless there is a decimal in the number (0.0050 has two sigfigs; 4100.0 has five sigfigs).
Trailing zeros in a whole number without a decimal are not significant (1000 has one SigFig).
For conversions - use the same number of sigfigs as the original value.
Rounding after solving a problem:
If the original number was 2.140 x 107
Four sigfigs (2.140); therefore, the answer must also have four sigfigs.
If the product was 1.150672 x 105, then it would need to be rounded to 1.151 x 105.
Examples:
0.00456 - 3 sigfigs
2000 - 1 sigfig
1.20 × 10² - 3 sigfigs
150.0 - 4 sigfigs
Match the correct number of significant figures to each value.
| Draggable item | arrow_right_alt | Corresponding Item |
|---|---|---|
1.20 x 103 | arrow_right_alt | 4 |
0.00456 | arrow_right_alt | 3 |
100.0 | arrow_right_alt | 3 |
How many significant figures will the answer to each have?
| Draggable item | arrow_right_alt | Corresponding Item |
|---|---|---|
5.678 + 2.4 | arrow_right_alt | 4 |
12.22 - 0.002 | arrow_right_alt | 3 |
3.00 x 4.5 | arrow_right_alt | 3 |
How many molecules are in 2.50 moles of NaCl?
Initial calculation (not rounded):
Calculation rounded using sigfigs:
How many grams of CO2 are in 0.100 moles of it?
Initial calculation (not rounded):
Calculation rounded using sigfigs:
How many molecules of H2O are in 5.00 moles of it?
Initial calculation (not rounded):
Calculation rounded using sigfigs:
How many grams are in 3.00 moles of C6H12O6?
Initial calculation (not rounded):
Calculation rounded using sigfigs:
How many molecules are in 0.250 moles of KCl?
Initial calculation (not rounded):
Calculation rounded using sigfigs:
How many molecules are in 50.0 grams of NaCl?
Initial calculation (not rounded):
Calculation rounded using sigfigs:
How many molecules are in 10.0 g of CO2?
Initial calculation (not rounded):
Calculation rounded using sigfigs:
How many molecules are in 25.0 g of H2O?
Initial calculation (not rounded):
Calculation rounded using sigfigs:
How many molecules are in 100.0 g of C6H12O6?
Initial calculation (not rounded):
Calculation rounded using sigfigs:
How many grams are in 5.00 x 1024 molecules of KCl?
Initial calculation (not rounded):
Calculation rounded using sigfigs: