500 grams of an unknown substance gains 23000 J of heat as it is heated from a temperature of 250C to 1250C. Using mathematical computation and the chart below, determine the identity of the unknown substance.

The given substance is cast iron.

Explanation:

Given data:

Mass of substance = 50 g

Heat absorbed = 23000 J

Initial temperature = 250°C

Final temperature = 1250°C

Which metal is this = ?

Solution:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 1250°C -  250°C

ΔT = 1000°C

23000 j = 50 g ×c ×1000 °C

23000 J = 50,000 g. °C×c

c = 23000 J /50,000 g. °C

c = 0.46 J/g.°C

The given substance is cast iron.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.