If the density of an ideal gas at stp if found to be 0.0902 g/l, what is its molar mass?
2 answers:
<u>Answer:</u> The molar mass of the gas is 2.02 grams.
<u>Explanation:</u>
We are given:
Density of gas = 0.0902 g/L
At STP conditions:
1 mole of gas occupies 22.4 L of volume
And 1 mole of a substance is known as the molecular mass or molar mass of that substance.
To calculate the mass of gas, we use the equation:
Putting values in above equation, we get:
Hence, the molar mass of the gas is 2.02 grams.
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First, we have to remember the molarity formula:
Part 1:
In this case, our solute is sodium nitrate (NaNO3), and we have the mass dissolved in water, then we have to convert grams to moles. For that, we need the molecular weight:
Then, we calculate the moles present in the solution:
Now, we have the necessary data to calculate the molarity (with the solution volume of 200 mL):
The molarity of this solution equals 0.2339 M.
Part 2:
In this case, we have the same amount (in moles and mass) of sodium nitrate, but a different volume of solution, then we only have to change it:
So, the molarity of this solution is 0.1701 M.
Answer:
The enthalpy change during the reaction is -199. kJ/mol.
Explanation:
Mass of solution = m
Volume of solution = 100.0 mL
Density of solution = d = 1.00 g/mL
First we have to calculate the heat gained by the solution in coffee-cup calorimeter.
where,
m = mass of solution = 100 g
q = heat gained = ?
c = specific heat =
= final temperature =
= initial temperature =
Now put all the given values in the above formula, we get:
Now we have to calculate the enthalpy change during the reaction.
where,
= enthalpy change = ?
q = heat gained = 2.242 kJ
n = number of moles fructose =
Therefore, the enthalpy change during the reaction is -199. kJ/mol.