If 89.6 joules of heat are needed to heat 20.0 grams of iron from 30.0°c to 40.0°c, what is the specific heat of the iron in jg?
1 answer:
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Answer:
19,26 kJ
Explanation:
The work done when a gas expand with a constant atmospheric pressure is:
W = PΔV
Where P is pressure and ΔV is the change in volume of gas.
Assuming the initial volume is 0, the reaction of 500g of Zn with H⁺ (Zn(s) + 2H⁺(aq) → Zn²⁺(aq) + H₂(g)) produce:
500,0g Zn(s)××
= 7,648 moles of H₂
At 1,00atm and 303,15K (30°C), the volume of these moles of gas is:
V = nRT/P
V = 7,648mol×0,082atmL/molK×303,15K / 1,00atm
V = 190,1L
That means that ΔV is:
190,1L - 0L = <em>190,1L</em>
And the work done is:
W = 1atm×190,1L = 190,1atmL.
In joules:
190,1 atmL× = <em>19,26 kJ</em>
I hope it helps!
Answer:
The equilibrium temperature of the system is 276.494 Kelvin.
Explanation:
Let consider the system formed by the sample of aluminium and water as a control mass, in which the sample is cooled and water is heated until thermal equilibrium is reached. The energy process is represented by First Law of Thermodynamics:
Where:
- Heat received by water, measured in joules.
- Heat released by the sample of aluminium, measured in joules.
Given that no mass is evaporated, the previous expression is expanded to:
Where:
,
- Mass of water and the sample of aluminium, measured in kilograms.
,
- Specific heats of the sample of aluminium and water, measured in joules per kilogram-Kelvin.
,
- Initial temperatures of the sample of aluminium and water, measured in Kelvin.
- Temperature which system reaches thermal equilibrium, measured in Kelvin.
The final temperature is now cleared:
Given that ,
,
,
,
and
, the final temperature of the system is:
The equilibrium temperature of the system is 276.494 Kelvin.