Mapooo You need to prepare 250. mL of a 0.650 M aqueous solution of sucrose C12H
ID: 574739 • Letter: M
Question
Mapooo You need to prepare 250. mL of a 0.650 M aqueous solution of sucrose C12H22011(aq), which is used frequently in biological experiments Which type of glassware should you lA use to make this solution (assuming B that the accuracy of the concentration is important)? 250 mL 200 mL 150 How should the correct amount of solute be obtained? 250 mL 100 O O Measure out xg of solid sucrose on a balance Measure out x cm of sucrose with a ruler Measure out x mol of solid sucrose on a molemeter Now that you have selected the correct unit above, what is the value of x? Number r= How should the solute and solvent be mixed in the container? O Fill the continer with water to the 250-mL mark, then add the solute O Add the solute, then fill the container to the 250-mL mark with water O Mix a small amount of water with the solute to dissolve it, then fill with water to the 250-mL markExplanation / Answer
i) I hope glassware type C is used to make the given solution.
Reason: To maintain the accuracy of the concentration, the neck of the flask should be narrow such that the rate of evaporation is slower in glassware type C compared to A and B.
ii) Measure out x g of solid sucrose on a balance.
iii) Molarity = no. of mol/volume in L
0.650 M = no. of moles of sucrose/(250*10-3 L)
i.e. The no. of moles of sucrose = 0.65 mol/L *0.25 L = 0.1625 mol
The molar mass of sucrose = 342 g/mol
No. of moles = mass/molar mass
i.e. 0.1625 mol = mass of sucrose/342 g mol-1
i.e. The mass of sucrose = 0.1625 mol*342 g mol-1 = 55.575 g
i.e. x = 55.575
iv) Mix a small amount of water with the solute to dissolve it, then fill with water to the 250-mL mark.
Explanation: First of all, the sucrose and a small amount of water should be shaken well to mix thoroughly and then fill with water up to the 250-mL mark.
Note: If you add water directly up to the mark 250-mL, then it's difficult to mix the solution thoroughly due to the narrow neck.