Answer:

Explanation:
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In this case, since this is a system in which the water is heated up and the metal is cooled down in a calorimeter which is not affected by the heat lose-gain process, we can infer that the heat lost by the metal is gained be water, it means that we can write:

Thus, in terms of masses, specific heats and temperatures we can write:

Whereas the equilibrium temperature is the given final temperature of 28.4 °C and we can compute the specific heat of the metal as shown below:

Plugging the values in and since the density of water is 1.00 g/mL so the mass is 80.0g, we obtain:

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Explanation:
Gravitational potential energy
= mgh = (45kg)(9.81N/kg)(2m) = 882J.
Answer:
10.49
Explanation:
3MgO + 2Fe — Fe2O3 + 3Mg
n(Fe2O3) = m/M
=15/159.69
=0.9393199324mol
1 Mol of Fe2O3 = 2 moles of Fe
Therefore n(Fe) =2 * 0.9393199324
=0.1878639865mol
m(Fe) = n*m.m
= 0.1878639865 * 55.8
=10.4828g