A flask with a volume of 125.0 mL contains air with a density of 1.298 g/L. what is the mass of the air contained in the flask<span>The given are: </span>
<span><span>1. </span>Mass = ?</span><span><span /></span>
<span><span>2. </span>Density = 1298 g/L</span>
3. Volume = 125mL to L
a. 125 ml x 0.001l/1ml = 0.125 L
<span>Formula and derivation: </span><span><span>
1. </span>density = mass / volume</span> <span><span>
2. mass </span>= density / volume</span>
<span>Solution for the problem: </span><span><span>
1. mass = </span></span> <span> 1298 g/L / 0.125 L = 10384g
</span>
The purpose of using distilled water in the cuvette of the spectrophotometer is to calibrate the instrument. It is generally considered that distilled water shows zero absorbance and 100 % transmittance. So, to zero out the absorbance of compounds other than the analyte being determined, distilled water is used as a blank.
If the unknown being determined is prepared using ethanol as the base solution, the blank used must be ethanol. This is because absorbance if any from the solvent, ethanol must be zeroed out as when the measurement of the actual unknown is being made, the absorbance of the solvent does not interfere.
Answer : The pressure of hydrogen gas is, 739.3 torr
Explanation :
As we are given:
Vapor pressure of water = 18.7 torr
Barometric pressure = 758 torr
Now we have to calculate the pressure of hydrogen gas.
Pressure of hydrogen gas = Barometric pressure - Vapor pressure of water
Pressure of hydrogen gas = 758 torr - 18.7 torr
Pressure of hydrogen gas = 739.3 torr
Therefore, the pressure of hydrogen gas is, 739.3 torr