1.Both hydrogen and methane are used as gaseous fuels. Their combustion reactions are given below.

2H2+O2-->2H2O; H= -484kJ

CH4+2O2-->CO2+2H20; H=-803kJ

Which of these 2 fuels would produce the larger amount of heat per gram fuel.

explaining would be nice.. :D

2.when methane burns in the presence of oxygen, CO2 and H2O is produced.

a. identify the bonds that break and form in this reaction.

b. Compare the amount of energy required to break the bonds in the reactants with the amount of energy released during the formation of the bonds in the products.


14.NH3+H-->NH4; H=-53kJ

a.what amount of heat is evolved when 100mL of 0.10 mol L ammonia solution is added to 100mL of 0.10 mol L hydrochloric acid in a beaker?

b.If it takes 4.18J to change the temperature of 1g of this solution by 1 Celsius, determine the temperature change that would accompany this reaction. Assume 1 mL of the solution has a mass of 1g.

c. Why would this temperature change not be observed in this experiment?

I don't understand what this question is trying to ask. :confused:

Thx in advance. :D

1.Both hydrogen and methane are used as gaseous fuels. Their combustion reactions are given below.

2H_2+O_2 \rightarrow 2H_2O H= -484kJ

CH_4+2O_2 \rightarrow CO_2+2H_20 H=-803kJ

Which of these 2 fuels would produce the larger amount of heat per gram fuel.



The equations actually give you the amount of heat per mole (or multiple mole) of fuel. We'll calculate heat per gram.

The molecular weight of H2 is 2. 2 moles of hydrogen burn to yield 484 kJ of heat.

2\,moles \times \frac {2\,grams}{mole}= 4 grams

-484kJ \div 4 grams = -121 \frac {kJ}{g}

The molecular weight of CH4 is 16. 1 mole of methane burns to yield 803 kJ of heat

1\,moles \times \frac {16\,grams}{mole}= 16 grams

-803kJ \div 16 grams = -50.2 \frac {kJ}{g}

When using heat per gram of fuel, hydrogen wins hands down.



2.when methane burns in the presence of oxygen, CO2 and H2O is produced.

a. identify the bonds that break and form in this reaction.

b. Compare the amount of energy required to break the bonds in the reactants with the amount of energy released during the formation of the bonds in the products.


Hydrogen, H2, can be written H-H with a single bond between the hydrogen atoms.
Methane, CH4 can be written H-C-H with two more CH bonds (vertical and horizontal).

CO2 can be written O=C=O with double bonds between the carbon and each oxygen.
H2O can be written H-O-H with single bonds between the oxygen and each hydrogen.

To form CO2 and H2O, some chemical bonds have to be broken; some have to be formed. I think you can figure out which ones.



NH_3+H^+ \rightarrow NH_4^+; H=-53kJ

a.what amount of heat is evolved when 100mL of 0.10 mol L ammonia solution is added to 100mL of 0.10 mol L hydrochloric acid in a beaker?

b.If it takes 4.18J to change the temperature of 1g of this solution by 1 Celsius, determine the temperature change that would accompany this reaction. Assume 1 mL of the solution has a mass of 1g.

c. Why would this temperature change not be observed in this experiment?


a. Ammonia gas (NH3) reacts with acids (H+) (you forgot the +) to form the ammonium ion. You're given 100 mL of 0.10 Molar ammonia solution. You can figure out how many moles react from this equation:

100\, mL \times \,\frac {0.10\,moles}{L} \times \frac {1L}{1000\,mL}= ?? moles

You know that 53 kJ of heat is evolved for 1 mole. You can easily calculate what amount of heat is released for? Moles (multiply).

b. for each 4.18 J, the temperature rises by 1 C. Divide the heat evolved by 4.18 J/deg C.

c. probably very small (you verify this). It could be measured in a sensitive calorimeter.