The density of magnesium is 1.7/cm3, and the density of iron is 7.9g/cm3. Consider a block of iron with a mass of 819 g. What is the mass of a block of magnesium that has the same volume as the block of iron?
Answer:
83°C
Explanation:
The following were obtained from the question:
M = 40g
C = 4.2J/g°C
T1 = 91°C
T2 =?
Q = 1300J
Q = MCΔT
ΔT = Q/CM
ΔT = 1300/(4.2x40)
ΔT = 8°C
But ΔT = T1 — T2 (since the reaction involves cooling)
ΔT = T1 — T2
8 = 91 — T2
Collect like terms
8 — 91 = —T2
— 83 = —T2
Multiply through by —1
T2 = 83°C
The final temperature is 83°C