Question

1) If the same quantity of energy is added to 10.00 g pieces of gold, magnesium and platinum, all originally at 25°C, which metal will have the highest final temperature? What is that temperature?

C_Au = 25.41 J/mol°C, C_Mg = 24.79 J/mol°C, C_Pt = 25.95 J/mol°C

2) Acetylene (C₂H₂) and benzene (C₆H₆) have the same empirical formula and benzene can be synthesized from acetylene:

3C₂H_2(g)-------------> C₆H_6(l)

Find ∆H_reaction for the synthesis of benzene using the ∆H_f° values below.

C₆H₆   –3267.4 kJ/mole

C₂H₂ –1299.4 kJ/mole.

Is the synthesis of benzene from acetylene endothermic or exothermic?

Answer 1

Ans 1.

Q = m.c.Delta T

where Q is heat

m is mass of substance in grams

c is specific heat capacity of the material

And delta T is the change in temperature.

Now as you may see from the formula , the change in temperature is inversely related to specific heat , when all other values are kept constant.

So the substance with lowest specific heat will have highest temperature i.e. Magnesium

To calculate that temperature , the amount of energy is required , which will be put in the formula , Q = m.c.delta T