Amount of kWh used to heat water

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SUMMARY

The discussion focuses on calculating the energy consumption in kilowatt-hours (kWh) required to heat 285 liters of water using the equation kWh = (Q * Cj * ∆t) / T. Two scenarios are analyzed: heating from +5 °C to +75 °C, which results in 23.2 kWh, and from +20 °C to +75 °C, yielding 18.2 kWh. The variable T, representing time, is clarified as 3600 seconds for the calculations. The conversion of energy units is also discussed, emphasizing the relationship between joules and kilowatt-hours.

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Homework Statement



How much kWh is beeing used to heat 285 liters of water in a water heater from:
1. + 5 °C to + 75 °C
2. + 20 °C to + 75 °C

Homework Equations



Found this equation:

kWh = (Q*CJ*∆t)/T

The Attempt at a Solution



Q = liter = 285
Cj = heat capacity = 4,18
∆t = 70 for 1. And 55 for 2.
T = is the time, but I'm not sure what to use here, so I used 3600.

So my answer was:
1. 23,2 kWh
2. 18,2 kWh

I have no clue if this is right or wrong because of the variable T. What is correct here?
 
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kWh is a unit of energy, so just calculate the energy using QC∆t, and then convert.

1 kWh = 1 kW * 1 hr = 1000 J/s * 3600 s = 3,600,000 J

So 1 J is?

Then just convert!
 

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