Unit 3 - Titration
NaOH was titrated against acetic acid which had a conc of 0.5020M and 25mL aliquot was used. End point was 19.30mL of NaOH. Calculate the [NaOH]
0.6503M
Identify the oxidising agent in the reaction below:
3Br2 + 6OH- --> BrO3- + 5Br- + 3H2O
Br2 is both the oxidising and reducing agent
what catalyst is required when alkenes react with water
H3PO4
what is the name of the bond formed between two monosaccharides
glycosidic bond (-O-)
Determine the pH of a 0.01 M solution of a hydrofluoric acid, HF, which is a weak acid (Ka = 6.8 x 10-4).
Hint: write the Ka expression
pH = 2.58
calculate the pH of 0.04M KOH
pOH = -log [OH-] = -log (0.04) = 1.40
pH + pOH = 14
pH = 12.6
what's the distinguishing test used to differentiate primary, secondary and tertiary alcohols?
explain the colour changes
acidified dichromate/permanganate
Cr2O72-/H+ = primary + secondary (orange to green)
MnO4-/H+ = primary + secondary (purple to colourless)
explain 2 differences between amylose and amylopectin
amylose = helices. amylopectin = branched/spherical
amylose = alpha (1-4).
amylopectin = also alpha (1-6)
2A + B <---> C + D
1 mol of A and 0.8 mol of B are placed in a 2L container and allowed to reach equilibrium. The resulting mixture had 0.2M of D. What is the value of Kc?
Hint: RICE
Kc = 20
I 0.5 0.4 0 0
C -2x -x +x +x
E 0.5-2x 0.4-x 0+x 0+x
x = 0.2
At equilibrium: A = 0.1M, B = 0.2M, C = 0.2M, D = 0.2M
Kc = 0.2 x 0.2 / (0.1)^2 x 0.2 = 20
a galvanic cell consists of Zn and Pb electrodes.
Use the data booklet to determine which species will likely be oxidised (ie the stronger reducing agent)
Zn = more negative = stronger reducing agent and therefore will get oxidised
show the reaction pathway for turning a propane to propan-1-ol
propane + Br2 (+UV) --> 1-bromopropane + KOH (aq) --> propan-1-ol
what are the reduction and oxidation equations for a hydrogen fuel cell under acidic conditions?
ox: H2 --> 2H+ + 2 e-
red: O2 + 4H+ + 4e- --> 2H2O
E (Ag+ /Ag) = +0.80V
E (Ni2+/Ni) = -0.24 V
Which cell will be the reduction half-cell and which will be the oxidation half cell?
Reduction = Ag+/Ag (more p+)
Oxidation = Ni2+/Ni (more n-)
name the ester made when hexanoic acid reacts with butanol
butyl hexanoate
salicylic acid + acetic anhydride --> aspirin + ethanoic acid
Calculate the mass of salicylic acid required to produce 8.25g of aspirin, if the percentage yield is 60%.
M(aspirin) = 180.17
M(salicylic acid) = 138.13
theoretical = 8.25g/0.60 = 13.75g
n(aspirin) = m/M = 13.75/180.17 = 0.0763 mol = n(salicylic acid)
m (salicylic acid) = n x M = 0.0763 x 138.13 = 10.5g