Zadania z chemii IB HL

Znalezionych zadań: 505

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A student stirred 0.030 mol of solid sodium hydrogencarbonate into 40 $\mathrm{cm^3}$ of a 1.0 $\mathrm{mol\,dm^{-3}}$

solution of ethanedioic acid.

\ce{H2C2O4(aq) + 2NaHCO3(s) -> Na2C2O4(aq) + 2CO2(g) + 2H2O(l)}

The temperature of the solution fell from…

What are the limiting reactant and the theoretical yield of hydrogen when 0.30 mol of aluminium reacts with 0.60 mol of hydrochloric acid? $\ce{2Al(s) + 6HCl(aq) -> 2AlCl3(aq) + 3H2(g)}$ In each option the limiting reactant is given first and the theoretical…

For which of these changes is $\Delta S$ negative? A. $\ce{2SO2(g) + O2(g) -> 2SO3(g)}$ B. $\ce{NaNO3(s) -> NaNO3(aq)}$ C. $\ce{Zn(s) + 2HCl(aq) -> ZnCl2(aq) + H2(g)}$ D. $\ce{CuCO3(s) -> CuO(s) + CO2(g)}$

The table shows standard enthalpies of combustion. Substance $\Delta H_\mathrm{c}^\ominus$ / $\mathrm{kJ\,mol^{-1}}$ $\ce{C4H10(g)}$ −2878 $\ce{C3H6(g)}$ −2058 $\ce{CH4(g)}$ −891 Which expression gives the enthalpy change, in $\mathrm{kJ\,mol^{-1}}$ , of the…

Which are units for rate of reaction? A. $\mathrm{s\,mol^{-1}\,dm^{3}}$ B. $\mathrm{mol\,dm^{-3}\,min}$ C. $\mathrm{mol\,dm^{-3}\,min^{-1}}$ D. $\mathrm{mol\,min^{-1}}$

A reaction is spontaneous at low temperatures but becomes non-spontaneous when the temperature is raised. Which combination of signs of $\Delta H$ and $\Delta S$ is consistent with this behaviour? A. $\Delta H > 0$ and $\Delta S > 0$ B. $\Delta H < 0$ and…

Which reaction has the largest positive entropy change? A. $\ce{2SO2(g) + O2(g) -> 2SO3(g)}$ B. $\ce{NH4Cl(s) -> NH3(g) + HCl(g)}$ C. $\ce{H2(g) + Cl2(g) -> 2HCl(g)}$ D. $\ce{NaOH(aq) + HCl(aq) -> NaCl(aq) + H2O(l)}$

Which changes increase the rate of the reaction? $\ce{CaCO3(s) + 2HCl(aq) -> CaCl2(aq) + H2O(l) + CO2(g)}$ I. Grinding the calcium carbonate into a fine powder II. Using a larger volume of hydrochloric acid of the same concentration III. Warming the…

Which route to chloroethane has an atom economy of 100 %? A. $\ce{C2H5OH + PCl5 -> C2H5Cl + POCl3 + HCl}$ B. $\ce{C2H6 + Cl2 -> C2H5Cl + HCl}$ C. $\ce{C2H5OH + HCl -> C2H5Cl + H2O}$ D. $\ce{C2H4 + HCl -> C2H5Cl}$

One route to 2-bromopropane is the substitution of propane by bromine in ultraviolet light. $\ce{C3H8(g) + Br2(g) -> C3H7Br(g) + HBr(g)}$ ( $\ce{C3H8}$ = 44.11 $\mathrm{g\,mol^{-1}}$ , $\ce{Br2}$ = 159.80 $\mathrm{g\,mol^{-1}}$ , $\ce{C3H7Br}$ = 123.00…