Answer is: molar mass of xylene 106,18 g/mol.
m(xylene) = 7,94 g.
m(cyclohexane) = 132,5 g.
T (solution) = - 4,9 °C.
Tf(cyclohexane) = 6,5 °C, frezing point.
Kf(cyclohexane) = 20,2 K·kg/mol; cryoscopic constant.
ΔT(solution) = 6,5°C - (-4,9°C) = 11,4°C = 11,4 K.
M(xylene) = Kf · m(xylene) ÷ m(cyclohexane) · ΔT(solution).
M(xylene) = 20,2 K·kg/mol · 7,94 g ÷ 0,1325 kg · 11,4 K.
M(xylene) = 106,18 g/mol.
Answer:
H + ions are attracted to the cathode , gain electrons and form hydrogen gas. OH - ions are attracted to the anode , lose electrons and form oxygen gas.
It is important in gravimetric analysis to add an excess amount of precipitating ions to a solution containing an analyte because it helps to determine the mass of the analyte.
<h3>What is Gravimetric analysis?</h3>
This is a method which is used in the determination of the quantitative determination of the ion being analyzed(analyte) based on its mass.
Adding an excess amount of precipitating ions to a solution containing an analyte will make it easier for the mass of an analyte to be determined.
It is also important for the precipitate to be a pure substance with a definite and known composition which therefore makes it the most appropriate reason.
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Option B is true , the same number of moles of solute in both solution is the same.
<h3>What is Molarity? </h3>
Molarity is the ratio of no of moles as per liter solution. It is denoted by M and SI unit is also M or moles/litre.
Molarity = no . Of moles/Volume (L)
In this question the amount of solution is increased means the volume is increased from 500-700ml it is increased , Molarity is inversly proportional of Volume
it will decrease if volume increase. Adding water do affect the concentration of the solution. The no. Of moles of solute remains because there no increament in amount of NaCl .
Hence ,option B is more correct
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