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Math in chemistry
What are two types of numbers?
What are significant figures/sig digs/sig figs?
What are the three rules for determining significant figures for a measurement and give
an example of each:
Determine the number of significant figures in each of the following numbers:
1 ) 0.02 cm
2) 0.020 cm
3) 501 mm
4) 501.0 mm
5) 5000 cm
6) 5000.0 cm
7) 6051.00 cm
8) 0.0005 m
Use scientific notation to represent all the measurements above.
Calculate the following USING the correct number of significant figures:
1) 1.35 m x 2.467 m
2) 1035 m2/42m
3) 12.01 mL + 35.2 mL + 6 mL
4) 55.46 g – 28.9 g
5) 0.021 cm x 3.2 cm x 100.1 cm
6) 0.15 cm + 1.15 cm + 2.051 cm
7) 150 L3/4L2
8) 505 kg -450.25 kg
9) 1.252 mm x 0.115 mm x 0.012 mm
10) 1.278 x 103 m2/1.4267 x 102 m
What are 2 ways to solve most problems?
Dimensional Analysis/Factor-Label Method
Method for converting from one unit to another
Uses a conversion factor which is always equal to 1 because it is an equality.
Ex) How many seconds are in one school week?
Math in chemistry
Ex) How many miles are in 729 km?
Practice. Show all work.
5.5 kg = _____ lbs.
2.5 yds = _____in.
1.3 yr = _____hr (1 year = 365 days)
3 moles = _____________ molecules (6.02 x 1023 molecules = 1 mol)
2.5 x 1024 molecules = ______ moles
5 moles oxygen = ___ L o oxygen (1 mole = 22.4 L)
100. L = ______ moles
50. L oxygen = _________________ molecules of oxygen
What is the density of a liquid that has a mass of 30g and a volume of 50 mL?
If glycerin has a density of 1.26 g/mL, what is the volume of 30 g of glycerin?