A 5-g sample of impure magnesium carbonate is reacted with an excess of hydrochloric acid: MgCO3 (s) 1 2HCl (aq) MgCl2 (aq) 1 H2O (l) 1 CO2 ( g)
1250 cm3 of carbon dioxide is collected at rtp.
a How many moles of CO2 are produced?

b What mass of pure magnesium carbonate would give this volume of carbon dioxide? (Ar : C 5 12, O 5 16, Mg 5 24.)

c Calculate the % purity of the 5-g sample.

Imagine that a new planet is discovered with two moons of equal mass: moon a and moon b. the mass of the new planet is greater than the combined mass of its moons. moon a is farther away from the new planet than moon b. what is the planet's gravitational pull on moon a compared to the planet's gravitational pull on moon b? the planet's gravity repels moon a with a greater force than it repels moon b, which is why moon a is farther away. the gravitational pull on moon b is greater than on moon a because moon b is closer to the new planet than moon a. the gravitational pull on moon b is greater than on moon a because moon b is farther away from the new planet than moon a. the gravitational pull on moon a is the same as the gravitational pull on moon b because distance does not affect the planet's gravity.