When a 3.22 g sample of an unknown hydrate of sodium sulfate, na2so4 ⋅ h2o(s), is heated, h2o (molar mass 18 g) is driven off. T
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Answer:
The molar mass of the compound is:- 168.82 g/mol
The molar mass of the gas is:- 16.38 g/mol
Explanation:
(a)
Using ideal gas equation as:
where,
P is the pressure
V is the volume
n is the number of moles
T is the temperature
R is Gas constant having value = 0.0821 L.atm/K.mol
Also,
Moles = mass (m) / Molar mass (M)
Density (d) = Mass (m) / Volume (V)
So, the ideal gas equation can be written as:
Given that:-
Pressure = 20 kPa = 20000 Pa
The expression for the conversion of pressure in Pascal to pressure in atm is shown below:
P (Pa) = P (atm)
20000 Pa = atm
Pressure = 0.1974 atm
Temperature = 330 K
d = 1.23 kg/m³ = 1.23 g/L
Molar mass = ?
Applying the equation as:
0.1974 atm × M = 1.23 g/L × 0.0821 L.atm/K.mol × 330 K
⇒M = 168.82 g/mol
<u>The molar mass of the compound is:- 168.82 g/mol</u>
(b)
Given that:
Pressure = 152 Torr
Temperature = 298 K
Volume = 250 cm³ = 0.25 L
Using ideal gas equation as:
R =
Applying the equation as:
152 Torr × 0.25 L = n × 62.3637 L.torr/K.mol × 298 K
⇒n = 0.002045 moles
Given that :
Mass of the gas = 33.5 mg = 0.0335 g
Molar mass = ?
The formula for the calculation of moles is shown below:
Thus,
<u>The molar mass of the gas is:- 16.38 g/mol</u>
Answer : The correct option is, the negative log of the hydroxide ion concentration.
Explanation :
pOH : It is defined as the negative logarithm of hydroxide ion concentration. It is a measure of the alkalinity of the solution.
Formula used :
is the concentration of
ions.
When pOH is less than 7, the solution is alkaline.
When pOH is more than 7, the solution is acidic.
When pOH is equal to 7, the solution is neutral.