Chap 10: Water
What is the units for specific heat capacity?
J g-1 oC-1
Define 'amphiprotic species'.
species that can donate or accept protons (can act as an acid or a base)
What do you call a species that causes oxidation to happen?
oxidising agent (oxidant)
A saline bag contains 4.30 g of NaCl dissolved in 0.500 L of aqueous solution. Calculate the concentration, in %(m/v) of NaCl in the saline bag.
0.860%(m/v)
known volume of solution dispensed from the burette needed to reach the end point
titre
Explain whether covalent bonds or hydrogen bonds are broken when liquid water evaporates into steam.
The intermolecular bonds, hydrogen bonds are broken.
Covalent bonds between atoms in the H2O molecule are still intact.
Write the equation for H3PO4 acting as an acid in water.
H3PO4 (aq) + H2O (l) -> H2PO4 - (aq) + H3O+ (aq)
A metal, M, undergoes the following reaction.
It is dissolved when placed in a solution of P2+ ions.
It does not reaction when placed in a solution of Q2+ ions.
What is the order of the metals from weakest reducing agent to strongest reducing agent?
(e.g: A < B < C)
P < M < Q
0.2 g of NaCl is dissolved in 500 L of aqeuous solution. Express this in ppm.
0.4 ppm
Calculate energy required, in kJ, required to fully convert 100 g of liquid water to steam.
226 kJ
Pb(NO3)2 (aq) + Zn (s) --> Zn(NO3)2 (aq) + Pb (s)
a) Write the two half equations for the overall reaction. Identify which is oxidation and reduction.
b) State the oxidising agent.
a) reduction: Pb2+ (aq) + 2e- --> Pb (s)
oxidation: Zn (s) --> Zn2+ (aq) + 2e-
b) Pb2+ (aq)
When 45 kJ of heat energy is added to a mass of water, the temperature changed by 5.00 oC. Caclulate the mass of water used.
2.15 x 10^3 g
Calculate the concentration of NaOH, in M, if titres of 24.45 ml, 24.78 ml, 24.69 ml & 24.65 ml of 0.300 M HCl were used to titrate 20.0 ml of NaOH solution.
c(NaOH) = 0.371 M
Explain why the pH of the oceans is decreasing and identify one possible consequence of this decrease on marine life.
- Excess CO2 emitted by human activities --> absorbed by the oceans --> formation of carbonic acid --> lowers pH
- decrease shell thickness in marine animals --> death of marine creatures