Which has more molecules?
1 answer:
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c) 29.8 mL
d) 5375 mL
e)
Explanation:
c)
We can solve this problem by using Boyle's Law, which states that:
"For a fixed mass of an ideal gas kept at constant temperature, the pressure of the gas is inversely proportional to its volume"
Mathematically:
where
p is the pressure of the gas
V is its volume
We can rewrite the formula as
For the gas in this problem:
is the initial pressure
is the initial volume
is the final pressure (using the conversion factor
)
Solving for V2, we find the final volume:
d)
We can solve this part by using again the equation:
Where in this case we have:
is the initial pressure
is the initial volume
is the final pressure
Converting into atmospheres,
And solving for V2, we find the final volume:
e)
As before, we use Boyles' Law:
In this part we have:
is the initial pressure of the gas
is the initial volume of the gas
1 torr is equivalent to 1 mmHg, so the conversion factor is the same as before, therefore the final pressure in atmospheres is:
And so, the final volume of the krypton gas is:
Answer:
155 kJ of energy will be released.
Explanation:
The (
in some textbooks) here stands for standard enthalpy change per mole reaction. To find the amount of energy released in this reaction, start by finding the number of moles of this reaction that will take place.
How many <em>moles</em> of atoms in 4.72 grams of carbon?
Relative atomic mass data from a modern periodic table:
- C: 12.01.
.
The coefficient of carbon in the equation is one. In other words, each mole of the reaction will consume one mole of carbon. Oxygen is in excess. As a result, of carbon will support
of the reaction.
How much energy will be released?
The value here is negative. But don't panic.
is the same as the chemical potential energy of the reactants minus the products in one mole of the reaction.
means that the chemical potential energy drops by
during each mole of the reaction (with the coefficients as-is.) Those energy difference will be released as heat. In other words, one mole of the reaction will release
of energy.
The 4.72 grams of carbon will support of this reaction. How much heat will that
of reaction release?
.
As a side note, the mass of carbon 4.72 grams is the least significant data in this question. There are three significant figures in this value. As a result, keep more than three significant figures in calculations but round the final result to three significant figures.