Other Chemistry Answers

The average atmospheric pressure at sea level is 1.012 × 106 dynes/m2. The value of

g (acceleration of gravity) at sea level is 980 cm/sec2. What is the mass in kg of the

column of air having a cross-sectional area of 1.00 cm2 at the earth’s surface and

extending to the limits of the atmosphere? (Recall that the dyne is a unit of force,

and force = mass × acceleration of gravity.)

1. 14g of kno2

a bottle of hydrogen peroxide also known as agua oxigenada is labeled 3% (v/v). How many ml of agua oxigenada are in a 400ml bottle of this solution?

A 10.0 g-sample of potassium bromide is treated with perchloric acid solution. The reaction mixture is cooled and solid KClO4 is removed by filtering, then it is dried and weighed. KBr (aq)+HClO4 (aq) = KClO4 (s)+HBr (aq) The product weighed 8.8 g. What was the percent yield

a) Calculate the molarity of a 5 ppm pesticide solution if the molar mass of the pesticide

435 g/mol.

b) Seawater contains 3.90 x 10¯ 3 ppb of dissolved gold. What volume (in litres) of this seawater would contain 100 g of gold?

Silver metal can be prepared by reducing its nitrate, AgNO 3 with zinc according to the

following equation:

Zn(s) + 2 AgNO 3 (aq) → Zn(NO 3 ) 2 (aq) + 2 Ag(s)

What is the percent yield of the reaction if 93.5 grams of Ag was obtained from 150.5 grams

of AgNO 3 ?

Aspirin (acetylsalicylic acid) is widely used to treat pain, fever, and inflammation. In COVID 19 treatment it is also given as a blood thinner to prevent blood clotting for patients showing very high D-dimer value.

It is produced from the reaction of salicylic acid with acetic anhydride with sulphuric acid as a protonating agent.

In an industry, 10.00 kg of salicylic acid is mixed with 10.00 kg of acetic anhydride.

a) Which reactant is limiting? Which is in excess?

b) What mass of excess reactant is left over?

c) What mass of aspirin is formed assuming 100% yield (Theoretical yield)?

d) What mass of aspirin is formed if the reaction yield is 70.0%?

a) Write the balanced equation for the reaction of acetic acid with aluminium hydroxide to form water and aluminium acetate:

b) Using the equation determine the mass of aluminium acetate that can be made if we start the reaction with 150 grams of acetic acid and 300 grams of aluminium hydroxide.

c) What is the limiting reagent?

d) How much of the excess reagent will be left over after the reaction is complete?

9. Two elements, Sodium and Chlorine, react to form crystals out of a water solution. What can be said about the space between the atoms in the crystal lattice? 

A. The atoms pack so tightly that they completely flatten against each other

B. In between the atoms is air.

 C. Water molecules get stuck in between the sodium and chlorine atoms.

 D. There is nothing but space between the atoms in the crystal