Advertisements
Advertisements
Question
Define Molality.
Advertisements
Solution
Molality (m) is defined as the number of moles of the solute per kilogram (kg) of the solvent. It is expressed as:
Molality (m) = `"Moles of solute"/"Mass of solvent in Kg"`
Therefore, the unit of molality is mole per kg (mol kg−1).
If nB moles of solute are dissolved in W grams of solvent, then
Molality = `"n"_"B"/"W" xx 1000`
APPEARS IN
RELATED QUESTIONS
Why is molality of a solution independent of temperature?
Define Mole fraction.
Define Mass percentage.
A solution of glucose in water is labelled as 10% w/w, what would be the molality and mole fraction of each component in the solution? If the density of solution is 1.2 g mL−1, then what shall be the molarity of the solution?
A solution is obtained by mixing 300 g of 25% solution and 400 g of 40% solution by mass. Calculate the mass percentage of the resulting solution.
An antifreeze solution is prepared from 222.6 g of ethylene glycol (C2H6O2) and 200 g of water. Calculate the molality of the solution. If the density of the solution is 1.072 g mL−1, then what shall be the molarity of the solution?
A sample of drinking water was found to be severely contaminated with chloroform (CHCl3) supposed to be a carcinogen. The level of contamination was 15 ppm (by mass):
- express this in percent by mass.
- determine the molality of chloroform in the water sample.
Nalorphene (C19H21NO3), similar to morphine, is used to combat withdrawal symptoms in narcotic users. Dose of nalorphene generally given is 1.5 mg. Calculate the mass of 1.5 × 10−3 m aqueous solution required for the above dose.
22.22 gram of urea was dissolved in 300 grams of water. Calculate the number of moles of urea and molality of the urea solution. (Given: a Molar mass of urea = 60 gram mol-1)
Molarity of the solution is ____________.
The sum of all mole fraction for a mixture is always equal to ____________.
Molarity of liquid HCl will be if the density of the solution is 1.17 gm/cc.
1 M, 2.5 litre NaOH solution is mixed with another 0.5 M, 3 litre NaOH solution. Then find out the molarity of the resultant solution:
An X molal solution of a compound in benzene has mole fraction of solute equal to 0.2. The value of X is ____________.
The molarity of the solution containing 7.1 g of Na2SO4 in 100 ml of aqueous solution is ____________.
An aqueous solution of glucose is 10% in strength. The volume in which 1 g mole of it is dissolved, will be:
2.5 litres of NaCl solution contain 5 moles of the solute. What is the molarity?
5 ml of N HCl, 20 ml of N/2 H2SO4 and 30 ml of N/3 HNO3 are mixed together and volume made to one litre. The normality of the resulting solution is:
25 ml of a solution of barium hydroxide on titration with a 0.1 molar solution of hydrochloric acid gave a titre value of 35 ml. The molarity of barium hydroxide solution was ______.
Mole fraction of the solute in a 1.00 molal aqueous solution is ____________.
The volume of 4 N HCl and 10 N HCl required to make 1 litre of 6 N HCl are ____________.
For preparing 0.1 N solution of a compound from its impure sample of which the percentage purity is known, the weight of the substance required will be:
A solution made by dissolving 40 g NaOH in 1000 g of water is ____________.
Which of the following units is useful in relating concentration of solution with its vapour pressure?
Out of molality (m), molarity (M), formality (F) and mole fraction (x), those which are independent of temperature are:
Which of the following is a correct statement for C2H5Br?
Define the following modes of expressing the concentration of a solution. Which of these modes are independent of temperature and why?
V/V (volume percentage)
Define the following modes of expressing the concentration of a solution. Which of these modes are independent of temperature and why?
ppm. (parts per million)
Define the following modes of expressing the concentration of a solution. Which of these modes are independent of temperature and why?
x (mole fraction)
Define the following modes of expressing the concentration of a solution. Which of these modes are independent of temperature and why?
M (Molarity)
Match List-I with List-II:
| List-I | List-II |
| A. ppm | I. molL-¹ |
| B. Molarity | II. No units |
| C. Molality | III. Independent of temperature |
| D. Mole fraction | IV. Very dilute solutions |
Choose the correct answer from the options given below:
Carbon percentage (by weight) in crude petroleum may be about
The number of electrons involved in the reduction of one nitrate ion to hydrazine is
The unit of ebullioscopic constant is
What is molarity of resulting solution obtained by mixing 8.5 L of 0.5 m urea solution and 500 ml of 2 m urea solution?
138 g ethyl alcohol is mixed with 72 g of water. The ratio of mole fraction of alcohol to water is ______.
250 mL of 0.5 M NaOH was added to 500 mL of 1 M HCl. The number of unreacted HCl molecules in the solution after complete reaction is ______ × 1021. (Nearest integer) (NA = 6.022 × 1023).
A given solution of H2O2 is 30 volumes. Its concentration in terms of molarity is ______.
The molarity of the solution prepared by dissolving 6.3 g of oxalic acid (H2C2O4 · 2 H2O) in 250 mL of water in mol L-1 is x × 10-2. The value of x is ______. (Nearest integer)
[Atomic mass: H : 1.0, C : 12.0, O : 16.0]
The mole fraction of a solute in a 100 molal aqueous solution is ______ × 10-2. (Round off to the Nearest Integer).
[Given :Atomic masses : H : 1.0 u, O : 16.0 u]
The depression in freezing point of water observed for the same amount of acetic acid, trichloroacetic acid and trifluoroacetic acid increases in the order given above. Explain briefly.
