1125 J of energy is used to heat 250 g of iron to 55 °C. The specific heat capacity of iron is 0.45 J/(g·°C). What was the temperature of the iron before it was heated?

55 °C
55 °C

35 °C
35 °C

45 °C
45 °C

20 °C

45 °C.

Explanation:

From the question given above, the following data were obtained:

Heat (Q) = 1125 J

Mass (M) = 250 g

Final temperature (T₂) = 55 °C

Specific heat capacity (C) = 0.45 J/gºC

Initial temperature (T₁) =?

The initial temperature of the iron can be obtained as illustrated below:

Q = MC(T₂ – T₁)

1125 = 250 × 0.45 (55 – T₁)

1125 = 112.5 (55 – T₁)

Divide both side by 112.5

1125/112.5 = 55 – T₁

10 = 55 – T₁

Collect like terms

10 – 55 = –T₁

–45 = –T₁

Multiply through by –1

45 = T₁

T₁ = 45 °C

Therefore, the initial temperature of the iron is 45 °C

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.