Zadania z chemii IB HL

The student pipetted 25.00 $\mathrm{cm^3}$ of the potassium hydroxide solution into a conical flask and titrated it with nitric acid, $\ce{HNO3(aq)}$, of concentration 0.1250 $\mathrm{mol\,dm^{-3}}$. The burette readings before and after the titration are…

Explain why the potassium hydroxide solution has to be standardized before it is used in the titration. Assume that there are no systematic errors in the procedure.

The student then used the potassium hydroxide solution standardized in 1c to titrate ethanoic acid, $\ce{CH3COOH}$, whose concentration was not known. (i) Neutralizing 25.00 $\mathrm{cm^3}$ of the acid required 40.00 $\mathrm{cm^3}$ of the standardized…

4.06 g of hydrated magnesium chloride, $\ce{MgCl2*6H2O}$ ($M_\mathrm{r}$ = 203), is dissolved in water to make 0.250 $\mathrm{dm^3}$ of solution. What is the concentration of chloride ions, in $\mathrm{mol\,dm^{-3}}$, in this solution? A. 0.0400 B. 0.0800 C.…

A student writing a report on chlorine as a disinfectant collects, from several websites and reference books, values for how much chlorine dissolves in pure water at various temperatures. Source Temperature / °C Solubility of chlorine A 5 1.18 g per 100…

A solution is prepared by dissolving 1.29 g of HA in water and making the volume up to $20.00\ \mathrm{cm^3}$. When the whole of this solution is titrated with $0.600\ \mathrm{mol\,dm^{-3}}$ sodium hydroxide, NaOH(aq), exactly $24.90\ \mathrm{cm^3}$ of the…

A cylinder contains 80 g of argon and 12.0 g of helium. What is the ratio of the number of argon atoms to the number of helium atoms in the cylinder? A. 0.15 B. 0.67 C. 1.5 D. 6.7

The enthalpy of combustion of $\ce{C15H32}$ is $-10\,040\ \mathrm{kJ\,mol^{-1}}$. (i) Calculate the maximum amount of energy that the complete combustion of 1.75 g of pentadecane can release. (ii) The energy from burning the 1.75 g sample is used to heat…