The following equation for the reaction of alum with barium chloride is not balanced. KAl(SO4)2•12H2O(aq) + BaCl2(s) → KCl(aq) + AlCl3(aq) + BaSO4(s) a) Balance the equation. Calculate the mass (g) of barium chloride needed to react with 25 mL of a 0.10 M alum solution. b) In an experiment 1.02 grams of BaSO4(s) was produced. Calculate the percent yield of BaSO4(s).

A. 1.04g of BaCl2.

B. Percentage yield of BaSO4 is 87.6%

Explanation:

A. The balanced equation for the reaction. This given below:

KAl(SO4)2•12H2O(aq) + 2BaCl2(s) → KCl(aq) + AlCl3(aq) + 2BaSO4(s) + 12H2O(l)

Next, we shall determine the number of mole in 25 mL of a 0.10 M alum. This is illustrated below:

Volume = 25mL = 25/1000 = 0.025L

Molarity = 0.1M

Mole =..?

Mole = Molarity x Volume

Mole of alum = 0.1 x 0.025 = 2.5x10¯³ mol.

Next, we shall convert 2.5x10¯³ mol of alum to grams.

Number of mole alum, KAl(SO4)2•12H2O = 2.5x10¯³ mol

Molar Mass of alum, KAl(SO4)2•12H2O = 39 + 27 + 2[32+(16x4)] + 12[(2x1) + 16]

= 39 + 27 + 2[32 + 64] + 12[2 + 16]

= 39 + 27 + 2[96] + 12[18]

= 474g/mol

Mass of alum, KAl(SO4)2•12H2O =..?

Mass = mole x molar mass

Mass of alum, KAl(SO4)2•12H2O = 2.5x10¯³ x 474 = 1.185g

Next, we shall determine the mass of alum and BaCl2 that reacted and the mass of BaSO4 produced from the balanced equation. This is illustrated below:

Molar mass of alum, KAl(SO4)2•12H2O = 474g

Mass of alum, KAl(SO4)2•12H2O from the balanced equation = 1 x 474 = 474g

Molar mass of BaCl2 = 137 + (35.5x2) = 208g/mol

Mass of BaCl2 from the balanced equation = 2 x 208 = 416g

Molar mass of BaSO4 = 137 + 32 + (16x4) = 233g/mol

Mass of BaSO4 from the balanced equation = 2 x 233 = 466g

Summary:

From the balanced equation above,

474g of alum reacted with 416g of BaCl2 to produce 466g of BaSO4.

Finally, we can calculate the mass of BaCl2 needed for the reaction as follow:

From the balanced equation above,

474g of alum reacted with 416g of BaCl2.

Therefore, 1.185g of alum will react with = (1.185 x 416)/474 = 1.04g of BaCl2.

Therefore, 1.04g of BaCl2 is needed for the reaction.

B. Determination of the percentage yield of BaSO4(s).

We'll begin by calculating the theoretical yield of BaSO4. This is illustrated below:

From the balanced equation above,

474g of alum reacted to produce 466g of BaSO4.

Therefore, 1.185g of alum will react to produce = (1.185 x 466)/474 = 1.165g of BaSO4.

Therefore, the theoretical yield of BaSO4 is 1.165g.

Finally, we shall determine the percentage of BaSO4 as follow:

Actual yield of BaSO4 = 1.02g.

Theoretical yield of BaSO4 = 1.165g.

Percentage yield of BaSO4 =..?

Percentage yield = Actual yield /Theoretical yield x 100

Percentage yield of BaSO4 = 1.02/1.165 x 100

Percentage yield of BaSO4 = 87.6%

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).