how to measure mass without Q?
a 100°C hot water is added to a 300g of water with initial temperature of 0°C until it reaches 40°C.
what is the initial mass of the added hot water?
- VamanLv 75 months ago
300gm water needs energy= 40 s *300. This must be given by
(100-40) s mass of hot water. mass of hot water= 1200/60=200 gm This is the answer given below. s is called a the specific heat of water.
- billrussell42Lv 75 months ago
energy required to warm the 300 g of water:
E = 4.186 J/gC x 300 x (40–0) = 50232 J
that must equal energy to cool the added mass
E = 50232 J = 4.186 J/gC x M x (100–40)
M = 200 g
actually the 4.186 J/gC terms cancel and you can use a symbol instead.
E = SH x 300 x 40 = 12000•SH
M = 12000•SH / 60•SH = 200 g
specific heat of water is 4.186 kJ/kgC = 4.186 J/gC
= 1 calorie/gC = 5.375 J/mol·K = 1 Btu/lb-F