Wednesday

July 30, 2014

July 30, 2014

Posted by **Fai** on Tuesday, December 25, 2012 at 12:31am.

Calculate the molarity of the solution.

My calculation

10g/58g/mol = 0.173M

0.173M/025L =0.689M

Given the density of the solution is 0.9864g/ml. Calculate the molality of the solution. The right answer 0.7233m/kg

Who helps

- chemistr -
**MathMate**, Tuesday, December 25, 2012 at 10:08amIn scientific calculations, it is important to know how accurate you'd like your answers. If you see a number like 0.9864g/ml, it means 4 significant figures are expected, so you have to carry your calculations to at least 5 significant digits, and then round off to 4 for the final answer.

Except for the number of significant digits, your calculation of molarity is correct.

Molality is defined as the ratio of the number of moles of solute to the mass of solvent.

For this problem, we need to find the mass of solvent (mass of solute is known, 10 g). Since the final volume is known (250 ml), so is the density (0.9864), the mass of the*solution*is therefore

m(solution) = 250*0.9864=246.60 g

Next calculate 10 g of NaCl is equivalent to how many moles (M), using accurate atomic masses.

The molality is then

M mol /(1000 g/kg /(246.6 g - m g)

- chemistr - correction -
**MathMate**, Tuesday, December 25, 2012 at 10:12amThe molality is then

M*mol*/(1000*g/kg*/( m -10*g*)

**Related Questions**

chemistry - 10g of nacl were added to 10ml of water. the resulting solution was ...

chem - Calculate the final concentration of a. 4.0 L of a 4.0 M HNO3 solution is...

Food Analysis - 1.If 0.5l of 5M solution of CU(NO3) is diluted to a volume of 0...

chemistry - A 2.5 g sample of NaOH (Mw = 40.00) was dissolved in water to give a...

Chemistry - You weigh out 196.07mg ferrous ammounium sulfate (FW 392.14) to ...

chemistry - 5.85g of sodium chloride is dissolved in 250mL of solution. ...

chem - an aq. solution(NaCl) made by using 133g diluted to a total solution ...

Chemistry - If you add enough water to 175.0 mL of a .15 M NaCl solution until ...

Chemistry - If 50.0mL of 1.60M HCl was added to 50.0mL of 1.80M NaOH, calculate ...

Chemistry - If 50.0mL of 1.60M HCl was added to 50.0mL of 1.80M NaOH, calculate ...