q=smDT E=mc2
c=3.00x108m/s sCu=.385
J/g°C sH2O=1.00cal/g°C=4.184J/g°C
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1 Classify the following as primarily (P)hysical
or (C)hemical changes. Circle P or C.
a) Formaion of a snow flake P C Physical
b) Dissolving sugar in water P C Physical
c) A leaf turning yellow P C Chemical
2 Copper oxide (CuO) consists of 79.9% copper.
How many grams of Copper (II) oxide can be formed from 1.80g of copper?
Two ways to do this:
1) Dimensional analysis: 1.80g Cu x (100 g CuO)/(79.9
g Cu)= answer
Note that the term, (100 g CuO)/(79.9 g Cu), is just the definition
of a percent.
2) Or equation defining percent, that is: %=(part/whole)x100
so: 79.7%=[1.80g Cu/(M g CuO)]x100 where M g is the mass of the CuO
in grams
3 How many Joules are required to raise
the temperature of 15.00 g of copper from 4.00°C to 100.0°C?
q = sCumDT
=.385 J/g°C x 15.00 g s (100°C -4.00°C) =
4 6.00 g of a substance at 10.0°C absorbs
13.0 calories of heat and achieves a temperature of 90.0°C. What is
the specific heat of the substance?
q=smDT solving for s gives s= q/(mDT)
= 13.0 cal/(6.00g x (90.0°C - 10.0°C) =
5 According to Einstein, mass and energy can be interconverted.
If the burning of 2.00 pounds of sugar in oxygen gives off 7.72x106
J, what is the difference in mass between the reactants and products of
the combustion.
E = mc2 Since m in this equation the mass that was converted
into energy, m represents the mass lost when the reaction occurs, or the
difference between the mass of the reactants and mass of products. Solving
for m gives: m=E/c2.
m=E/c2 = 7.72x106 J/(3.00x108)2=