Question

A block of copper of unknown mass has an initial temperature of69.6?C . The copper is immersed in a beaker containing 90.4g ofwater at 22.7?C . When the two substances reach thermalequilibrium, the final temperature is 24.4?C

What is the mass of the copper block?

Express your answer with the appropriateunits.

(a)

Calculate ?Hrxn for the following reaction:
CH4(g)+4Cl2(g)?CCl4(g)+4HCl(g)
Use the following reactions and given ?H?s.
C(s)+2H2(g)?CH4(g)?H=?74.6kJC(s)+2Cl2(g)?CCl4(g)?H=?95.7kJH2(g)+Cl2(g)?2HCl(g)?H=?184.6kJ

Express your answer using one decimalplace.

(b)

For each of the following, determine the value of ?H2in terms of ?H1.

A+B?2C,?H1
2C?A+B,?H2=?

Express your answer in terms of?H1.

A+1/2B?C,?H1
2C?2A+B,?H2=?

Express your answer in terms of?H1.

A?B+2C,?H1
1/2B+C?1/2A,?H2=?

Express your answer in terms of?H1.

(c)

Consider the following generic reaction: A+2B?C+3D, with?H = 171kJ . Determine the value of ?H for eachof the following related reactions.

3A+6B?3C+9D

C+3D?A+2B

12C+32D?2A+B

(d)

Consider the following reaction.
2 A + 3 B ? D ?H _rxn = 45.7 kJ
What is ?H _rxn for the followingreaction?
2 D ? 4 A + 6 B

	?23.8 kJ
	?45.7 kJ
	91.4 kJ
	?91.4 kJ