332 ❯ STEP 5. Build Your Test-Taking ConfidenceQuestion 4The following equipment is available for the determination of the molar mass of an unknown solid mono-
protic acid, HA. Assume the unknown acid is a weak acid.analytical balance thermometer beaker(s) support stand and clamp
stoppers glass tubing hot plate pipette(s)
test tube(s) stopwatch wire gauze flask(s)
buret pH meter graduated cylinderIn addition to this equipment there is standardized hydrochloric acid, HCl, solution and unstandardized
sodium hydroxide, NaOH, solution available and a suitable acid-base indicator such as phenolphthalein.
(a) Which of the above equipment is necessary for this experiment?
(b) Describe how the above equipment may be used to calculate the molar mass of the unknown solid.
(c) How would you calculate the Ka of the unknown acid?Current collectorElectrolyteCurrent collectorLithium
Oxygen
++++Metal
Graphic layer+ + ++ ++ +++++
+++++++++++++++++++
+++++++++++++Question 5The above schematic is one form of a lithium ion battery. The negative electrode (on the left) consists of
graphite with lithium ions trapped between carbon layers. The positive electrode (on the right) is a layered
metal oxide that allows lithium ions to enter the solid. The electrolyte is a lithium salt dissolved in an
organic solvent. The negative electrode has the approximate composition LiC 6 , and the positive electrode
can reach a composition of LiCoO 2 in a fully discharged battery. The half-reactions are:
xLiC 6 (s) → x Li+ + x e– + x C 6
Li1–xCoO 2 + x Li+ + x e– → LiCoO 2
(a) What is the balanced net ionic equation for the reaction?
(b) Why is it necessary to use an organic solvent for the electrolyte and not water?
(c) What is the oxidation state of cobalt in LiCoO 2? Write the electron configuration for this cobalt ion
in the ground state.GO ON TO THE NEXT PAGE20-Moore_PE01_p307-340.indd 332 31/05/18 1:58 pm