Counting particles by mass: The mole

(b) A variety of ions are dissolved in the water of the Salton Sea. The concentrations of the major ions are shown in the table below, based on two different sources (both scientific journals). Ion Concentration / $\mathrm{g\,dm^{-3}}$, based on Source 1…

(e) The propanoic acid obtained by the distillation was an aqueous solution with a volume of 22.5 $\mathrm{cm^3}$. Three 5.00 $\mathrm{cm^3}$ samples of this solution were titrated with 0.200 $\mathrm{mol\,dm^{-3}}$ $\ce{NaOH}$ to determine the accurate…

How many ions are present in 142 g of $\ce{Na2SO4}$? $M(\ce{Na2SO4}) = 142\ \mathrm{g\,mol^{-1}}$ A. 1 B. 3 C. $6.02 \times 10^{23}$ D. $1.81 \times 10^{24}$

What is the empirical formula of an alcohol with 60.0 % mass carbon and 13.4 % mass hydrogen? A. $\ce{C3H7}$ B. $\ce{C6H16O2}$ C. $\ce{C3H8O}$ D. $\ce{C2H6O}$

Which volume of oxygen is required to react fully with 40.0 cm3 of butane to ensure complete combustion? $\ce{2C4H10(g) + 13O2(g) -> 8CO2(g) + 10H2O(g)}$ A. 520 cm3 B. 260 cm3 C. 130 cm3 D. 40.0 cm3

Determine the mass of sodium thiosulfate pentahydrate, $\ce{Na2S2O3 * 5H2O}$, needed to prepare 250.0 $\mathrm{cm^3}$ of a 0.2000 $\mathrm{mol\,dm^{-3}}$ solution.

Explain how the 0.2000 $\mathrm{mol\,dm^{-3}}$ solution is prepared in a volumetric flask from the weighed solid.

Suggest how to prepare 100.0 $\mathrm{cm^3}$ of a 0.05000 $\mathrm{mol\,dm^{-3}}$ sodium thiosulfate solution from the 0.2000 $\mathrm{mol\,dm^{-3}}$ solution.

Before use, the EDTA solution was standardized against a standard solution of $\ce{Cu^2+}$ ions. An accurately weighed piece of pure copper wire was dissolved in the minimum volume of concentrated nitric acid and the mixture was warmed gently until no more…

Anhydrous copper(II) chloride, $\ce{CuCl2}$, takes up water vapour from the air, so it cannot be weighed out accurately to make a standard solution. Suggest a laboratory procedure that would remove all of the absorbed water from a sample of solid $\ce{CuCl2}$…