Writing Chemical Formula Worksheet With Answer Key - Spes Unica Page 18
ADVERTISEMENT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28LI 10
Formula mass in grams
The formula mass of a substance is worked out by adding the relative
atomic masses of all the elements present in the formula.
1. Write the formula for the compound.
2. Determine how many of each atom are in the compound. If there is a
number outside any brackets, multiply the number of atoms in the
bracket by this number. If there is no number, assume it is one.
3. Multiply the number of atoms by its atomic weight. (Every teacher is
different but my students must round the atomic weight to the tenth’s
place.
4. Add your results, don’t forget to add g for grams
Example 1: Calculate the formula mass of calcium chloride.
1.
CaCl
2
2.
Ca = 1
Cl = 2
3.
1 Ca = 1 x 40 = 40
2 Cl = 2 x 35∙5 = 71
4.
40 + 71 = 111g
Example 2: Calculate the formula mass of calcium carbonate.
1.
CaCO
3
2.
Ca = 1
C = 1
0 = 3
3.
1 Ca = 1 x 40 = 40
1 C = 1 x 12 = 12
3 O = 3 x 16 = 48
4.
40 + 12 + 48 = 100g
18
ADVERTISEMENT
0 votes
Related Articles
Related forms
Related Categories
Parent category: Education