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(c) After 30 minutes, the student stopped heating the mixture and titrated a sample of the solution remaining in the flask with NaOH to determine the experimental yield of propanoic acid. Explain why the titrated sample will give an incorrect value for the…
(d) The student used distillation to obtain pure propanoic acid from the reaction mixture. State two impurities, apart from unreacted propan-1-ol, that were present in the propanoic acid before distillation.
(i) State the number of protons, electrons and neutrons in . (ii) State the full electron configuration for . (iii) The relative atomic mass, Ar, of Rb is 85.47. Determine the relative mass of the first isotope of Rb to four…
(i) Explain why Rb has a lower first ionization energy than strontium, Sr. (ii) Outline why Rb has a lower electronegativity than potassium, K.
(i) Write the equation for the reaction of Rb with water, H2O, including state symbols. (ii) Describe the type of bonding in Rb and in H2O, and explain how the valence electrons in each produce that type of bond.
Bromine (Ar = 79.90) consists of two isotopes, and . What is the relative abundance of ? A. 10 % B. 45 % C. 55 % D. 90 %
Calculate the change in temperature for trial 5 and its uncertainty. Give the temperature change to a suitable number of decimal places and the uncertainty to a suitable number of significant figures.
The student decided to ignore the uncertainty in the mass of ethanol burnt when calculating the specific energy. Discuss whether this decision is valid, using the percentage uncertainties for trial 5.
Calculate the specific energy of ethanol for trial 5, in J g−1. Use sections 1 and 2 of the data booklet. mwater = 120.0 g
Determine the mean specific energy of ethanol from the five trials, explaining your method. If you did not obtain an answer to (c), use 8000 J g−1 for trial 5; this is not the correct value.