Friday
March 27, 2015

Homework Help: Chemistry

Posted by Mattt K on Sunday, October 25, 2009 at 5:17am.

Are these correct?

1. What is the formula mass for Mg(ClO3)2?
mg=24.31
cl=35.45 x 2 = 70.9
o=16 x 6 = 96
24.31+70.9+96= Answer:191.2 amu

2.How many molecules of CO2 are in 4.5 moles of CO2?
4.5 x 6.022 x10^23=Answer 2.7x10^24

3.How many grams are in 9.21 moles of H2CO3?
h=1.008 x2=2.016
c=12.01
o=16 x3=48
2.016+12.01+48=62.026g/mol
62.026 x 9.21=Answer 571g

4.How many moles are present in 88.2 grams of NaCl?
na=22.99
cl=35.45
22.99+35.45=58.44g/mol
88.2/58.44= Answer 1.51 mol

5. The percent composition of water is
A. 7% H, 33% O
B. 2 H, 1 O
C. 11% H, 89% O
D. 2 H, 16 O
E. 5.9%H, 94.1%O

water=h2o
h=1.008 x 2=2.016
0=16
2.016+16=18.016
2.016/18.016= 11%
16/18.016=89%
Answer= C. 11% H, 89% O

Thank you for the help. This has been a challenging chapter for me and I want to make sure I am doing it correctly.

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