489.88 was the initial temperature of the zinc.
Explanation:
Given :
mass of zinc = 7.5 grams
mass of water = 65 grams
specific heat = 0.390J/g°C
specific heat of water = 4.184 J/g°C
initial temperature of water = 20 degrees
Final temperature of zinc and water will be same as zinc is dissolved in water thus T2zinc and T2 water = 25 degrees
ΔTzinc = change in temperature T2 - T1
initial temperature of zinc =?
The formula used is
q = mcΔT for both water and zinc
putting the values for zinc and water in the formula:
mzinc x czinc x T2 zinc - T1 zinc = mwater x c water x T2 water- T 1 water
7.5 x 0.390 x ΔT zinc = -(65 x 4.184 x (25-20)
2.925 x ΔT zinc = -1359.8
ΔT zinc = - 464.88 degrees
Now,
ΔT zinc = T2 zinc - T1 zinc
T1 zinc = - 464.88-20
=489.88 degrees
489.88 degrees is the initial temperature of the zinc.
