# Chapter 5-7 Review Chemistry How many significant digits are in ```Chapter 5-7 Review
Chemistry
1. How many significant digits are in the following:
a. 1.004
b. 0.0003010
2. Calculate the following. Round answers to the correct significant digits
a. 1.34 x 2.0
b. 2.9010 + 387.45
3. Write the following in scientific notation.
a. 0.000381
b. 38100000
4. Convert the following:
a. 7.990daL to cL
b. 34.9nm to mm
5. Convert 34.9&deg;C to &deg;F
6. Convert 893&deg;C to K
7. An object has a mass of 45.69g and when you immerse it in water, the volume changes
from 67.89mL to 120.44mL.
a. What is the density of the object?
b. Will this object float in ethanol? (density=0.94g/mL) explain.
8. Is density a physical or chemical property? What about flash point (the temperature at
which something begins to burn)?
9. How many moles of Cu(NO3)2 are in 65.99g?
10. How many grams of N2O4 are in 5.66x1022 molecules?
11. What is the molar mass of Na2SO3?
12. What is the percent composition of (NH4)2S?
13. What is the percent composition of CaCO3?
1. Find the empirical formula of a compound that is 39.3 % carbon, 8.3% hydrogen, and
52.4% oxygen by mass.
14. Analysis of ibuprofen shows that it contains 75.7% carbon, 8.8% hydrogen, and 15.5%
oxygen. The molar mass of ibuprofen is 210g/mol. Determine the empirical and
molecular formula of ibuprofen.
Balance the equations
1.
H2 + O2 =&gt; H2O
2.
H3PO4 + KOH =&gt; K3PO4 + H2O
3.
K + B2O3 =&gt; K2O + B
4.
HCl + NaOH =&gt; NaCl + H2O
5.
Na + NaNO3 =&gt; Na2O + N2
6.
C + S8 =&gt; CS2
7.
Na + O2 =&gt; Na2O2
8.
N2 + O2 =&gt; N2O5
9.
H3PO4 + Mg(OH)2 =&gt; Mg3(PO4)2 + H2O
10.
NaOH + H2CO3 =&gt; Na2CO3 + H2O
11.
KOH + HBr =&gt; KBr + H2O
12.
H2 + O2 =&gt; H2O2
13.
Na + O2 =&gt; Na2O
14.
Al(OH)3 + H2CO3 =&gt; Al2(CO3)3 + H2O
15.
Al + S8 =&gt; Al2S3
16.
Cs + N2 =&gt; Cs3N
17. Mg + Cl2 =&gt; MgCl2
18.
Rb + RbNO3 =&gt; Rb2O + N2
19.
C6H6 +
O2 =&gt;
20. N2 + H2 =&gt; NH3
CO2 + H2O
```