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# Specific latent heat watch

1. Estimate how long a 3000W electric kettle would take to boil away 100g of water. The specific latent heat of vapourisation of water is 2.25 MJkg.

2. 1W = 1J/s
1MJ = 1,000,000J
3. (Original post by ArcaneMists)
1W = 1J/s
1MJ = 1,000,000J
How long would it take though?
4. (Original post by ArcaneMists)
1W = 1J/s
1MJ = 1,000,000J
Can you just give the proper answer please bro because I’m in year 9 and struggling with this
5. (Original post by mdmdwwdwdwd)
Can you just give the proper answer please bro because I’m in year 9 and struggling with this
Try working it out yourself or you won't improve. Find out how much energy is needed to raise the temperature of 100g of water by 1. It takes 2.25MJ to raise the temperature of 1kg of water by 1. Then you know that 3000J/s, so you will be able to find how long it takes to boil water (100C)
6. (Original post by ArcaneMists)
Try working it out yourself or you won't improve. Find out how much energy is needed to raise the temperature of 100g of water by 1. It takes 2.25MJ to raise the temperature of 1kg of water by 1. Then you know that 3000J/s, so you will be able to find how long it takes to boil water (100C)
Ok but is there an equation to work this out...we haven’t done this at school yet, we’re doing this next lesson. I’ll try and work it out and I’ll ask whether I get the right solution in a couple of hours:
7. (Original post by ArcaneMists)
Try working it out yourself or you won't improve. Find out how much energy is needed to raise the temperature of 100g of water by 1. It takes 2.25MJ to raise the temperature of 1kg of water by 1. Then you know that 3000J/s, so you will be able to find how long it takes to boil water (100C)
8. (Original post by ArcaneMists)
1W = 1J/s
1MJ = 1,000,000J
So I did 225 kJ / 3 kJ / second= 75 seconds. Is this correct??
9. (Original post by mdmdwwdwdwd)
So I did 225 kJ / 3 kJ / second= 75 seconds. Is this correct??
Ya I believe so
10. (Original post by ArcaneMists)
Ya I believe so
Really I got it correct???

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