Chemistry HELP!

Question

An office heater puts out 2010 Btus (British thermal units) of energy in the form of heat per hour. Given that 1 Btu =1.055 kJ, how many megajoules of energy in the form of heat can be produced per year (365 days) by the heater (assume continuous operation)?

Answer 1

Jakey,

 

The best way to do this is to use unit analysis as shown below:

 

 

2010 BTU   | 24 hrs  | 365 days | 1.055 kJ  | 1000 J | 1 MJ  = 1.86 x 10⁴ MJ      
    1 hr       | 1 day   |   1 year   |  1 BTU     |   1 kJ  | 10⁶ J

 

 

Using this method, continue using conversion factors until you get the final unit(s).

 

 

Hope this helps!

Answer 2

Jakey,

2010 BTU /hour is the output of the heater.

 

(2010 BTU/hour) * 24 hour   =  48240 BTU /day

 

(48240 BTU/day) * 365 day   =  17607600 BTU

 

1 BTU = 1.055 kJ

1000 kJ = 1 MJ

 

1 BTU = 1.055 * 10^-3 MJ   or .001055 MJ

 

17607600 BTU ((1.055 * 10^-3 MJ)/1 BTU)   = 1.858 * 10⁴ MJ    or  

 

18576.018 MJ exactly