i need your help fast
by balam23 on 10/17/05 at 02:45:48

Hola I need your help. I need calculate the energy in joules, therms, and kilowatt-hours that is required to heat 1 cup of water from 25 Celsius to 100 Celsius. Besides calculate the cost of heating 1cup of water using an electric stove when the electricity=$0 .1143/kW.hr and calculate the cost of heating 1 cup of water using a gas stove when the natural gas=$1.07/therm AND calculate the mass of natural gas that burns to boil 1 cup (240ml)of water from 25 celsius to 100 celsius ???

Re: i need your help fast
by Robert Fogt on 10/17/05 at 03:10:25

The formula would be: mass * temperature change * specific heat

mass is in grams, temperature change is in degree Celsius, and specfic heat is in calories/gram degree Celsius.

We know that the specific heat of water is 1 cal/gºC, so we just need to calculate the rest.

Water at 4º C has a density of 1 gram/cubic centimeter, while at 20º C it has a density of 0.998 gram/cubic centimeter. I will use the 20º C value, but keep in mind your answer may differ from your teachers as most textbooks use the 4º C value as an estimate.

1 cup of water at 20º C = 236.113826 grams

temperature change = 100º C - 25º C = 75º C

Now enter into the formula:

236.113826 grams * 75º C * 1 calorie/gram º C = 17708.53695 calories

You can now use the energy conversion page to convert that into which unit you need.

Re: i need your help fast
by balam23 on 10/17/05 at 11:23:50

you know, what other metal could be used besides aluminium that remove silver tarnish and waht is a chemical equation that represent that.

metals
by balam23 on 10/18/05 at 05:52:26

you know what is other metal besides aluminium that we could be used for remove silver tarnishand what is the chemical equation that represents the silver tarnish removing with this metal.