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April 16, 2014

Homework Help: Chemistry and I think some physics

Posted by Libby on Thursday, February 1, 2007 at 12:21pm.

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1. Classify each of the following pure substances as an element or a compound.
A) carbon
B) baking soda
C) nickel
D) gold
My answers: A) element B) compound C) element D) element


2. Perform the conversions
A) 345 Cal to kilowatt-hours
= 4x10^8 kWh

B) 23J to calories
= 5.5 cal

C) 5.7x10^3J to kilojoules
= 5.7kJ

D)326kj to joules
= 3.2x10^5J

3)Perform the following temperature conversions.

A) 102F to Celsius
= 38.8 C

B) 0(zero)K to Fahrenheit
= -459.4 F

C)48 C to F
=118.4F

D) 273K to C
= 0 C

4) calculate the amount of heat required to raise the temperature of a 27-g sample of water from 5 degrees celsius to 22 degrees Celsius.
= 1.91x10^3

5)An unknown metal is suspected to be gold. When 2.8J of heat are added to 5.6g of the metal, its temperature rises by 3.9 degrees Celsius. Are these data consistent with the metal being gold?
= 0.128 J/g C Yes its gold.





1. Classify each of the following pure substances as an element or a compound.
A) carbon
B) baking soda
C) nickel
D) gold
My answers: A) element B) compound C) element D) element

All of 1 ok.

2. Perform the conversions
A) 345 Cal to kilowatt-hours
= 4x10^8 kWh
Google shows 4E-4

B) 23J to calories
= 5.5 cal ok

C) 5.7x10^3J to kilojoules
= 5.7kJ ok

D)326kj to joules
= 3.2x10^5J I wouldn't drop the 6

3)Perform the following temperature conversions.

A) 102F to Celsius
= 38.8 C I get 38.88 which rounds to 38.9

B) 0(zero)K to Fahrenheit
= -459.4 F I get -459.67. Did you start with -273.15?

C)48 C to F
=118.4F ok

D) 273K to C
= 0 C ok

4) calculate the amount of heat required to raise the temperature of a 27-g sample of water from 5 degrees celsius to 22 degrees Celsius.
= 1.91x10^3 27*4.184*17=1.92E3

5)An unknown metal is suspected to be gold. When 2.8J of heat are added to 5.6g of the metal, its temperature rises by 3.9 degrees Celsius. Are these data consistent with the metal being gold?
= 0.128 J/g C Yes its gold. I assume you looked up the specific heat of gold. The value 0.128 J/g*C is correct.


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