At 20°c, an aqueous solution that is 24.0% by mass in ammonium chloride has a density of 1.0674 g/ml. what is the molarity of ammonium chloride in the solution? the formula weight of nh4cl is 53.50 g/mol.

Molarity = 4.79 M

Explanation:

Mass percentage -

Mass percentage of A is given as , the mass of the substance A by mass of the total solution multiplied by 100.

i.e.

mass % A = mass of A / mass of solution * 100  

Given,

24% by mass of ammonium chloride,

so,

100 g solution contains , 24 g of ammonium chloride,

mass of solution = 100g

and mass of the solute , i.e. , ammonium chloride = 24 g .

Hence,

Moles -

Moles are calculated as the given mass divided by the molecular mass.  

i.e. ,

moles = ( mass / molecular mass )

Given,

The molecular mass of ammonium chloride is 53.50 g /mol

moles of ammonium chloride = 24 g / 53.50 g /mol

moles of ammonium chloride = 0.449 mol

Density -

Density of a substance is given as the mass divided by the volume ,

Density = mass / volume ,

Volume = mass / density

Given ,

Density of ammonium chloride = 1.0764 g /mL

Calculated above , mass of solution = 100 g

volume of solution = 100 g / 1.0764 g/ mL

volume of solution = 93.69 mL

Since , 1 ml = 1/1000 L

volume of solution = 93.69 /1000 L

volume of solution = 0.09369 L

Molarity -

Molarity of a solution is given by the moles of solute per liter of the solution

Hence,  

M = moles of solute / volume of solution (in L)

As calculated above,

moles of ammonium chloride = 0.449 mol

volume of solution = 0.09368 L

Putting in the above formula

Molarity = 0.449 mol / 0/09368 L

Molarity = 4.79 M

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).