Advertisements
Advertisements
प्रश्न
Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040 (assume the density of water to be one).
Advertisements
उत्तर
Mole fraction of C2H5OH `=("Number of moles of ""C"_2"H"_5"OH")/"Number of moles of solution"`
`0.040="n"_("C"_2"H"_5"OH")/("n"_("C"_2"H"_5"OH")+"n"_("H"_2"O"))` .......(1)
Number of moles present in 1 L water:-
`"n"_("H"_2"O") = (1000 " g")/(18 " g"" mol"^-1)`
`"n"_("H"_2"O") = 55.55 " mol"`
Substituting the value of `"n"_("H"_2"O")` in equation (1),
`"n"_("C"_2"H"_5"OH")/("n"_("C"_2"H"_5"OH")+55.55)=0.040`
`"n"_("C"_2"H"_5"OH") = 0.040 "n"_("C"_2"H"_5"OH") + (0.040)(55.55)`
`0.96" n"_("C"_2"H"_5"OH") = 2.222 " mol"`
`"n"_("C"_2"H"_5"OH") = 2.222/0.96" mol"`
`"n"_("C"_2"H"_5"OH") = 2.314" mol"`
∴ Molarity of solution `=(2.314" mol")/(1 "L")`
= 2.314 M
APPEARS IN
संबंधित प्रश्न
A sample of drinking water was found to be severely contaminated with chloroform, CHCl3, supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass).
- Express this in percent by mass.
- Determine the molality of chloroform in the water sample.
Explain the term molality
Solve the following problem:
Find out the molar mass of the following compounds:
Copper sulphate crystal (CuSO4.5H2O)
(At. mass: Cu = 63.5; S = 32; O = 16; H = 1; Na = 23; C = 12; Fe = 56; N = 14)
Solve the following problem:
Write the following number in ordinary decimal form:
0.011 × 10−3
Solve the following problem:
Perform the following calculation. Round off your answer to two digits.
`(1.4xx10^9)/((2.77xx10^3)(3.76xx10^5))`
Solve the following problem:
Perform the following calculation. Round off your answer to three digits.
`(8.94xx10^6)/(4.35xx10^4)`
A 1.000 mL sample of acetone, a common solvent used as a paint remover, was placed in a small bottle whose mass was known to be 38.0015 g.
The following values were obtained when the acetone-filled bottle was weighed: 38.7798 g, 38.7795 g and 38.7801 g. How would you characterise the precision and accuracy of these measurements if the actual mass of the acetone was 0.7791 g?
Solve the following problem:
Your laboratory partner was given the task of measuring the length of a box (approx 5 in) as accurately as possible, using a metre stick graduated in milimeters. He supplied you with the following measurements:
12.65 cm, 12.6 cm, 12.65 cm, 12.655 cm, 126.55 mm, 12 cm.
State which of the measurements you would accept, giving the reason.
Solve the following problem:
Your laboratory partner was given the task of measuring the length of a box (approx 5 in) as accurately as possible, using a metre stick graduated in milimeters. He supplied you with the following measurements:
12.65 cm, 12.6 cm, 12.65 cm, 12.655 cm, 126.55 mm, 12 cm.
Give your reason for rejecting each of the others.
What are the favourable qualities given to gold when it is alloyed with copper or silver for the purpose of making ornaments?
When light is passed through water containing a few drops of milk, it shows a bluish tinge. This is due to the ______ of light by milk and the phenomenon is called ______. This indicates that milk is a ______ solution.
A child wanted to separate the mixture of dyes constituting a sample of ink. He marked a line by the ink on the filter paper and placed the filter paper in a glass containing water as shown in Fig.2.3. The filter paper was removed when the water moved near the top of the filter paper.
(i) What would you expect to see, if the ink contains three different coloured components?
(ii) Name the technique used by the child.
(iii) Suggest one more application of this technique.
Calculate the mass of sodium sulphate required to prepare its 20% (mass percent) solution in 100g of water?
If 500 mL of a 5 M solution is diluted to 1500 mL, what will be the molarity of the solution obtained?
What will be the molality of the solution containing 18.25 g of \[\ce{HCl}\] gas in 500 g of water?
What quantity (in mL) of a 45% acid solution of a monoprotic strong acid must be mixed with a 20% solution of the same acid to produce 800 mL of a 29.875% acid solution?
The molarity of urea (molar mass 60 g mol−1) solution by dissolving 15 g of urea in 500 cm3 of water is ______.
Molarity is ______.
