# Project #12640 - Chemistry

1.A sample of sodium reacts completely with 0.284kg of chlorine, forming 468g of sodium chloride. What mass of sodium reacted?
Express your answer to three significant figures and include the appropriate units

2.When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 13.2g of carbon were burned in the presence of 51.9g of oxygen, 16.7g  of oxygen remained unreacted. What mass of carbon dioxide was produced?
Express your answer to three significant figures and include the appropriate units.

3.Becky is going to take her dog for walk in the park, but before she leaves,  she watches the weather report. According to the weather report, it is 85.0 ?F outside. What is the outside temperature in kelvins?

4.Water (2230g ) is heated until it just begins to boil. If the water absorbs 5.31×105J of heat in the process, what was the initial temperature of the water?
5.How much heat energy is required to raise the temperature of 0.363kg of copper from 23.0 ?C to 60.0 ?C? The specific heat of copper is 0.0920 cal/(g⋅?C) .

6.If 125 cal of heat is applied to a 60.0-g piece of copper at 24.0?C , what will the final temperature be? The specific heat of copper is 0.0920 cal/(g⋅?C) .

7.                381 Cal to kilowatt-hours
E =
8.                       30. J to calories
9.                             5300 J to kilojoules
10.                                319 kJ to joules

Exercise 3.72
11.             The coldest temperature ever recorded in Iowa was -47 ?F on February 3, 1998.
a.Convert temperature to kelvin
b.Convert degree to celsius

12.A lead fishing weight with a mass of 57 g absorbs 146 cal of heat.
If its initial temperature is 43?C, what is its final temperature?
Enter the appropriate symbol for an isotope of phosphorus-32 corresponding to the isotope notation AZX.
13.On a mission to a newly discovered planet, an astronaut finds chlorine abundances of 13.85% for 35Cl and 86.15% for 37Cl . What is the atomic mass of chlorine for this location?

The mass of 35Cl is 34.9700amu . The mass of 37Cl is 36.9700amu .
Express your answer to two decimal places, and include the appropriate units.

14.The astronaut then measures the abundance of magnesium on the new planet, obtaining the following results:

Isotope     Abundance
(%)     Mass
(amu)
24Mg     78.99     23.99

25Mg
10.00     24.99
26Mg     11.01     25.98
What is the atomic mass of magnesium for this planet?
Express your answer to two decimal places, and include the appropriate units.

15.A helium nucleus has two protons and two neutrons.
How many electrons would it take to equal the mass of a helium nucleus?
16.Express these as ions    F
N

Mg
Na

17.Write the symbol for each isotope in the form AZX.
U−235
V−52P−32
Xe−144

18.Copper has two naturally occurring isotopes. Cu−63 has a mass of 62.939 amu and relative abundance of 69.17%.
Part A
Use the atomic weight of copper to determine the mass of the other copper isotope.
ymbol     Ion Commonly Formed     Number of Electrons in Ion     Number of Protons in Ion
F     --     --     9
--     Be2+     2     --
Br     --     36     --
Al     --     --     13
O     --     --     --
Fill in the boxes

 Subject Science Due By (Pacific Time) 09/21/2013 12:00 am
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