Question

What mass of water (in kg) at 1000 degree C could be completely vaporized with 2.70E^3 cal of energy: 5.00E^-3 kg How many joules (J) of energy are released when 6.80 times 103g of steam at 100.0 degree C are completely frozen to ice at 0.0 degree C: 2.05E^7 J Convert the H_f value for water (80 cal/g) to units of J/mol: 6025 J/mol How much energy (in J) is required to completely melt 205.0 mol of ice at 0.0 degree C: 1.235E^6 J How much heat is needed to raise the degree C totemperature125 degree C? of a How much heat is needed to raise the temperature of 85 g of potassium from 25 degree C to 2, 500 degree C?

Answer 1

(7)

Heat released in this complete conversion = 6800*2260 + 6800*4.184*(100-0) + 6800*334 = 20484320 J = 2.05*10⁷ J

(8)

1 cal = 4.184 J

1 mol water = 18 g

So,

80 cal/g = 80*(4.184*18) = 6024.96 J/mol = 6025 J/mol

Hope this helps !