Chemistry Answers

Thermite reaction is necessary to produce molten iron. this reaction involves Fe3O4 and Al and is described by:

8 Al + 3 Fe3O4 --> 9 Fe + 4 Al2O3

If 198.5 g Al and 365.5 g Fe3O4 are used, what mass of the excess reagent remains unused at the end of the reaction?

How many grams of KOH would be needed to make 50.0 mL of a 3.00 M KOH solution? 

What molarity of sugar water would be made if you diluted 100.0 mL of 6.0 M sugar water solution to a total volume of 500.0 mL? 

Ka for ethanoic acid is 1.7 × 10^–5 mol dm^–3 at 25 °C.

What is the pH of a 0.125 mol dm^–3 solution of ethanoic acid at this temperature?

How much heat is evolved when 1249 g of water condenses to a liquid at 100.°C?

Some hydrogen gas is collected over water at 20 ◦C. The levels of water inside and outside the gas-collection bottle are the same. The partial pressure of hydrogen is 509.4 torr. What is the barometric pressure at the time the gas is collected? Answer in units of torr. 

Helium gas is collected over water at 25◦C. What is the partial pressure of the helium, given a barometric pressure of 760 mm Hg? Answer in units of mm Hg. 

A sample of oxygen gas occupies a volume of 0.250 L at 740 torr pressure. What volume will it occupy at 800 toor pressure?

When calcium carbonate is heated ,it decomposes to produce quicklime and carbon dioxide

Calculate the volume of carbon dioxide produced at STP from the decomposition of 76g of CaCO3

Pentane is burnt with 96000 cm3 of oxygen gas at room temperature and pressure.

a) write the balance chemical equation for the reaction.

b) calculate the volume of carbon dioxide in cubic centimeters produce in the reaction at room temperature and pressure

c) calculate the mass of zinc needed to react with 50 cubic centimeters of 0.8 M of Hydrochloric acid