General Chemistry Answers

A 100 gram sample of a mixture was known to contain calcium carbonate and something else, if the sample was reported to contain 45% calcium which of the following could be the other substance in the mixture?

A) NaCl

B) CaO

C) CaI₂

D) Na₂CO₃

I know the answer is B but I don't know how they got that answer. I need someone to show me how they work it out.

A sample of foul-smelling gas has a density of 0.650 g/L at 250C and 757 mmHg. What is the molecular weight of the gas?

A sample of He gas kept in an inflatable balloon with a volume of 1.50 L and at a temperature of 27.0 ^oC exerted a pressure of 4.50 atm. What is the number of moles of He gas present? 

1. Calculate the ratio of the rate o effusion of methane gas, CH4 (g) to He (g) at

constant temperature and pressure. The molar masses or CH4 (g) and He (g)

are 16.0 g/mol and 4.0g/mol, respectively.

2. Calculate the ratio of the rate of effusion of hydrogen to the rate of effusion of

oxygen.

3. At a particular pressure and temperature, nitrogen gas effuses at the rate of

79 mL/s. Using the same apparatus at the same temperature and pressure,

at what rate will sulfur dioxide effuse?

4. Which of the following gases diffuse more slowly than oxygen?

F2, Ne, N2O, C2H2, NO, Cl2, H2S

A gas sample occupies a volume of 15.0 L at 30 ^oC and 750 torr. At what temperature will this gas occupy a volume of 25.0 L at the same pressure? 

A balloon has a volume of 4.0 L when at sea level pressure of 760 mmHg at room temperature. What will be its volume when inflated at an elevation where the atmosphere pressure is 700 mmHg and at the same temperature.

If 2.33 g of CuNO3 is dissolved in water to make a 0.250 M solution, what is the volume of the solution in millilitres

What is the density of an object that has a mass of 64kg and volume of 0.25m

A sample of oxygen, O2, occupies 32.2 mL at 30 °C and 452 torr. What volume will it occupy at –70 °C and the same pressure?

A sample of nitrogen, N2, occupies 45.0 mL at 27 °C and 600 torr. What pressure will it have if cooled to –73 °C while the volume remains constant?