Chemistry Homework- Stoichiometry: Volume and Particle Calculations

[SpoChi]

Chemistry Homework-- Stoichiometry: Volume and Particle Calculations

This is only to check my work, and I may be updating this post with more problems. There are ten questions total, and this is NOT graded. Therefore, the help I receive goes toward my understanding, not my score.

Homework Statement

What VOLUME of oxygen is produced from the decomposition of 5.67 x 10^24 molecules of water?
Balanced equation:
2H2O >decomposes to> 2H2 + O2

Homework Equations

6.02 x 10^23 molecules : 22.4L @STP for any gas
Mol-Mol ratio = 1 mol O2/ 2 mol H2O

The Attempt at a Solution

Trying to go along with dimensional analysis format.
(5.67 x 10^24)/(6.02 x 10^23) x 1 mol O2/ 2 mol H2O x 22.4L = 105.488L

Is the mol-mol ratio necessary? Without it, the answer comes out to 210.977L (rounded).

 

[epenguin]

This is only to check my work, and I may be updating this post with more problems. There are ten questions total, and this is NOT graded. Therefore, the help I receive goes toward my understanding, not my score.

Homework Statement

What VOLUME of oxygen is produced from the decomposition of 5.67 x 10^24 molecules of water?
Balanced equation:
2H2O >decomposes to> 2H2 + O2

Homework Equations

6.02 x 10^23 molecules : 22.4L @STP for any gas
Mol-Mol ratio = 1 mol O2/ 2 mol H2O

The Attempt at a Solution

Trying to go along with dimensional analysis format.
(5.67 x 10^24)/() x 1 mol O2/ 2 mol H2O x 22.4L = 105.488L

Is the mol-mol ratio necessary? Without it, the answer comes out to 210.977L (rounded).

Your answer is correct, or more cautiously, I get the same.
Why are you insecure?
A mole of gas occupies i.e. 6.02 x 10²³ molecules of gas, occupies 22.4 l at standard atmospheric pressure and temperature.
Independently of how many atoms are in each molecule.
I.e. 6.02 x 10²³ molecules of gas occupies 22.4 l under standard conditions - however many atoms there are in each molecule.

6.02 x 10²³ molecules of Argon (A), 6.02 x 10²³ molecules of oxygen (O₂) or 6.02 x 10²³molecules of ethane (C₂H₆) all occupy 22.4 l even though this is 6.02 x 10²³ atoms of A, 2X6.02 x 10²³ atoms of O₂, or 8X6.02 x10²³ atoms of ethane .

The rough basic reason for that is that any gas at a given pressure and temperature has the same average kinetic energy in the translational movement of the molecules. If it didn't then say you had a balloon of argon surrounded by oxygen at the same pressure then the argon atoms bounding of the inside of the balloon would transfer different momentum to it outwards than the oxygen atoms bouncing would transfer inwards. The baloon would expand or contract, in fact the pressure could not have been the same outside and inside to start with. I am not saying that is quite obvious, but that is what is shown in kinetic theory somewhere in your textbooks or maybe someone could explain better here.

 

[Blueshift5]

Great job on using dimensional analysis to solve this problem! Your approach is correct and it is always a good idea to include the mol-mol ratio in your calculations to ensure accuracy. In this case, since the balanced equation shows that 2 molecules of water decomposes to produce 1 molecule of oxygen, the mol-mol ratio is necessary to correctly convert the given number of molecules of water to the volume of oxygen produced. Keep up the good work!