Thermodynamics Qs

[Hexon]

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In EK GenChem, Q596 and 597, they ask

596) Larger objects made from the same substance have
a) greater specific heat
b) smaller specific heat
c) same specific heat
d) whether or not the specific heat increases or decreases for different amounts of the same substance depends on the substance

and

597) Larger objects from the same substance have

a) greater heat capacity
b) smaller heat capacity
c) same heat capacity
d) whether or not the heat capacity increases or decreases for different amounts of the same substance depends on the substance

now just to clariy, from the equation for specific heat: q=mc (delta T), shouldn't 596 be a) since if an object is larger, logically its mass would be greater and from the equation q=mc(delta T), q-its specific heat would likewise increase.

on the other hand for 597, heat capacity is C in the equation q=mc(delta T) isn't it? and that doesn't change right because it's an intensive property for the substance?

where did i go wrong?
thanks for the help, guys.

 

[Pisiform]

In EK GenChem, Q596 and 597, they ask

596) Larger objects made from the same substance have
a) greater specific heat
b) smaller specific heat
c) same specific heat
d) whether or not the specific heat increases or decreases for different amounts of the same substance depends on the substance

and

597) Larger objects from the same substance have

a) greater heat capacity
b) smaller heat capacity
c) same heat capacity
d) whether or not the heat capacity increases or decreases for different amounts of the same substance depends on the substance

now just to clariy, from the equation for specific heat: q=mc (delta T), shouldn't 596 be a) since if an object is larger, logically its mass would be greater and from the equation q=mc(delta T), q-its specific heat would likewise increase.

on the other hand for 597, heat capacity is C in the equation q=mc(delta T) isn't it? and that doesn't change right because it's an intensive property for the substance?

where did i go wrong?
thanks for the help, guys.

The idea is kinda goofy. Think about it in terms of units:

For the first question, they are talking about specific heat whose units are cal/g.K. The main idea is 'per gram' (per unit mass) which is going to remain same if the material is same. So even if mass is greater, the amount of heat absorbed per unit mass to bring about a change in Temp. T is same.

I think you are confusing this
Q = m c delta T

Q = heat added
m = mass
c = specific heat
T = Temp

For the second question, they are talking about Heat Capacity whose units are J/K and formula Q = C (delta T) so C = Q / delta T. If we have 2kg of water and 4kg of water and we have to heat it up to 75 Celsius .... the 4kg one would require more energy to reach the 75 Celsius temp than 2kg. So in 4kg one, Q is greater which means C is also greater than as compared to 2kg water. That is why it is an extensive property .... it is not per unit mass.

 

[Hexon]

thanks for the help, pisiform🙂