Calculate the amount of heat released in the combustion of 10.5 grams of Al with 3 grams of O2 to form Al2O3(s) at 25°C and 1 atm. ΔHfAl2O3(s) = ­−1676 kJ/mol HINT: What does ΔHfAl2O3(s) mean?

Answer : The amount of heat released in the combustion is, 209.5 kJ

Explanation :

First we have to calculate the moles of Al and .

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction will be:

From the balanced reaction we conclude that

As, 3 mole of react with 4 mole of

So, 0.188 moles of react with moles of

From this we conclude that, is an excess reagent because the given moles are greater than the required moles and is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of

From the reaction, we conclude that

As, 3 mole of react to give 2 mole of

So, 0.188 moles of react to give moles of

Now we have to calculate the amount of heat released in the combustion.

As, 1 mole of releases amount of heat = 1676 kJ

So, 0.125 mole of releases amount of heat =

Thus, the amount of heat released in the combustion is, 209.5 kJ

answer; talc and gypsum;

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.