A graduated cylinder with just water has a volume of 20.0 mL. When a 25.0 g piece of zinc alloy is added, the new volume is 23.2
1 answer:
Density of any substance is mass of the substance per unit volume. Density, d=m/V, where m is mass of the substance and V is the volume occupied by the substance. The amount of water displaced by an object when it is submerged in water equals the volume of the object. So, due to submerge of piece of zinc alloy in water present in graduated cylinder, water level rises. The increase in the volume of water is the volume of the zinc piece.
Volume of water in graduated cylinder before addition of zinc piece (v₁)= 20 ml, Volume of water in graduated cylinder after addition of zinc piece (v₂)= 23.2 ml, Rise in the volume due to submerge of the piece = (v₂ - v₁)ml= 23.2-20.0= 3.20 ml. So, volume of the piece is 3.20 ml and mass of the zinc piece is 25.0 g.
Hence density zinc alloy is equal to g/ml= 7.81 g/ml= 7.8 g/ml (expressed in two significant figure).
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<u>Answer:</u> The molality of non-electrolyte is 24.69 m
<u>Explanation:</u>
We are given:
Mole fraction of saturated aqueous solution = 0.310
This means that 0.310 moles of non-electrolyte is present.
Moles of water (solvent) = 1 - 0.310 = 0.690 moles
To calculate the mass from given number of moles, we use the equation:
Moles of water = 0.690 moles
Molar mass of water = 18 g/mol
Putting values in above equation, we get:
To calculate the molality of solution, we use the equation:
Where,
= Moles of solute (non-electrolyte) = 0.310 moles
= Mass of solvent (water) = 12.42 g
Putting values in above equation, we get:
Hence, the molality of non-electrolyte is 24.69 m