Questions to really learn!!!!!!!

• The enthalpy of hydration of Ca2+(g) is –1650 kJ mol–1

  Suggest why this value is less exothermic than that of Mg2+(g)

  $Ca^{2+}$ has bigger size to charge ratio

  Weaker attraction to $O^{\delta-}$ in water
• Give an equation, including state symbols, for the reaction of sodium with water

  Suggest why it is dangerous to react a similar piece of sodium with 10 cm3 of water in a boiling tube.

  $2Na(s)+$$2H_2O(l)\ \rightarrow\ 2NaO(s)+$$H_2(g)$

  Reactants could shoot out of tube
• Give an equation for the reaction of phosphorus(V) oxide with water.

  Suggest a pH for the solution formed

  $P_4O_{10}+$$6H_2O\ \rightarrow\ 4H_3PO_4$

  pH = 1
• An element in Period 3 forms an oxide that is insoluble in water. This oxide reacts with sulfuric acid and with aqueous potassium hydroxide. Give the formula for this oxide.

  Give an equation for the reaction of this oxide with sulfuric acid.

  $Al_2O_3$

  $Al_2O_3+$$3H_2SO_4\ \rightarrow\ Al_2\left(SO_4\right)_3+$$3H_2O$
• Explain why an aqueous solution containing [Fe(H2O)6] 3+ ions has a lower pH than an aqueous solution containing [Fe(H2O)6] 2+ ions.

  $Fe^{3+}$ is smaller

  $Fe^{3+}$ ions more polarising

  so more O-H bonds break
• What colour is $\left[Cu\left(H_2O\right)_6\right]^{2+}$solution?


  Blue
• What colour is $\left[Fe\left(H_2O\right)_6\right]^{2+}$solution?


  Green
• What colour is $\left[Fe\left(H_2O\right)_6\right]^{3+}$solution?


  Purple
• What colour is $\left[Al\left(H_2O\right)_6\right]^{3+}$solution?


  colourless
• Explain why the value of $K_w$ increases as the temperature increases.


  Equilibrium is endothermic.

  Equilibrium shifts to the right hand side to oppose the temperature increase.
• Suggest why the pH probe is washed with distilled water between each of the calibration measurements.

  Different solutions must not contaminate each other
• Explain why the volume of sodium hydroxide solution added between each pH measurement is smaller as the end point of the titration is approached.

  To avoid missing the end point
• Explain why the standard entropy for Carbon Dioxide is greater than that for carbon

  Carbon dioxide is a gas so is more disordered than carbon as a solid
• Explain why an aqueous is not used for a Lithium cell.

  Lithium would react with the electrolyte.
• What is the equation for the reaction between $\left[Cu\left(H_2O\right)_6\right]^{2+}$ and dilute $OH^-$?


  $\left[Cu\left(H_2O\right)_6\right]^{2+}+$$2OH^-\ \rightarrow\ Cu\left(H_2O\right)_4\left(OH\right)_2+$$2H_2O$
• What colour precipitate does $Cu\left(H_2O\right)_4\left(OH\right)_2$ Form?


  Blue
• What is the equation for the reaction between $\left[Fe\left(H_2O\right)_{^6}\right]^{2+}$and dilute $OH^-$


  $\left[Fe\left(H_2O\right)_{^6}\right]^{2+}+$$2OH^-\ \rightarrow\ Fe\left(H_2O\right)_4\left(OH\right)_2+$$2H_2O$
• What colour precipitate does $Fe\left(H_2O\right)_3\left(OH\right)_3$ form?


  Brown
• What colour precipitate does $Fe\left(H_2O\right)_4\left(OH\right)_2$ form?


  green
• What colour precipitate does $Al\left(H_2O\right)_3\left(OH\right)_3$ form?


  White
• What is the product of $Al\left(H_2O\right)_3\left(OH\right)_3$ and excess $OH^-$?

  And what colour does is the precipitate?

  $\left[Al\left(OH\right)_4\right]^-$

  Colourless
• What is the reaction of a $^{2+}$ ion with $CO_3^{2-}$?


  $\left[Cu\left(H_2O\right)_6\right]^{2+}\ +$$\ CO_3^{2-}\ \ \rightarrow\ \ CuCO_3\ +$$\ 6H_2O$
• What is the reaction of a $^{3+}$ ion with $CO_3^{2-}$? and what observation can you make?


  $\left[Fe\left(H_2O\right)_6\right]^{3+}\ +$$\ 3CO_3^{2-}\ \rightarrow\ Fe\left(H_2O\right)_3\left(OH\right)_3\ +$$\ 3CO_2\ +$$\ 3H_2O$

  effervesence
• Which hexaaqua metal ion complex has an incomplete ligand substitution with $NH_3$?


  $\left[Cu\left(H_2O\right)_6\right]^{2+}$
• What colour is $\left[CuCl_4\right]^{2-}$ solution?


  Yellow
• What colour is $\left[FeCl_4\right]^{2-}$ solution?


  Yellow
• Least soluble group 2 hydroxide

  $Mg\left(OH\right)_2$
• Most soluble group 2 hydroxide

  $Ba\left(OH\right)_2$
• Least soluble group 2 sulfate

  $BaSO_4$
• Most soluble group 2 sulfate

  $MgSO_4$
• Colour of Fluorine and physical state

  Yellow

  Gas
• Colour of Chlorine and physical state

  green

  gas
• Colour of bromine and physical state

  Red-brown

  Liquid
• Colour of iodine and physical state

  Grey

  solid
• Reaction of Chlorine water and Potassium Bromide

  Orange solution ($Br_2$) formed
• Reaction of Chlorine water and Potassium iodide

  Brown solution ($I_2$) formed
• Reaction of bromine water and potassium iodide

  Brown solution ($I_2$) formed
• Reaction of Chlorine and Water

  $Cl_2(g)$+$H_2O(l)$$\Leftrightarrow$$2H^+$$(aq)$+$Cl^-(aq)$+$ClO^-(aq)$
• What is the reaction between a halide and Sulfuric acid

  NaX + $H_2SO_4$ $\rightarrow$ $NaHSO_4$ + HX
• further reaction between HX and $H_2SO_4$


  HX + $H_2SO_4$ $\rightarrow$ $X_2$ + $SO_2$ + $2H_2O$