Bulgaria DZI Chemistry case studies
Bulgaria DZI Chemistry · Put your knowledge to work in context.
The Bulgarian State Matriculation Exam in Chemistry (ДЗИ по химия) is the school-leaving examination taken by students at the end of upper secondary education in Bulgaria. A result in chemistry is used for admission to university programmes in chemistry, pharmacy, medicine, biology, food technology and related fields, and it also serves as a formal record of achievement for candidates who simply want the subject on their diploma. The Bulgaria DZI Chemistry case studies are 5 cases and about 2,329 words.
1Identifying an Unknown Period 3 Element from Successive Ionisation Energies
A laboratory receives a sealed ampoule containing a sample of a Period 3 element, but the label has been lost. The sample is a brittle, lustrous solid that conducts electricity poorly.
512 words, about 3 min2Conductivity Evidence for Bonding Type in Three Unknown Chlorides
Three white crystalline solids, labelled X, Y and Z, are supplied with no other information. A student tests each: (i) melting point, (ii) electrical conductivity of the pure solid, (iii) conductivity of the molten liquid, and (iv) conductivity of the aqueous solution.
535 words, about 3 min3Stoichiometry and Limiting Reagent in a Precipitation Reaction
A technician mixes 250.0 mL of 0.200 mol/L barium chloride solution with 150.0 mL of 0.300 mol/L sodium sulfate solution. A white precipitate forms immediately.
385 words, about 2 min4Choosing a Route to a Pure Salt: Neutralisation, Precipitation or Displacement
A school needs a pure, dry sample of copper(II) sulfate crystals for a practical. Available starting materials: copper metal turnings, dilute sulfuric acid, copper(II) oxide powder, copper(II) carbonate powder, and sodium hydroxide solution.
456 words, about 2 min5Le Chatelier Reasoning in an Industrial Equilibrium
A simplified model of an exothermic equilibrium is studied in a closed vessel: A(g) + B(g) ⇌ C(g), ΔH = −92 kJ/mol. At 400 °C and 200 atm the equilibrium mixture contains 60% C by volume.
441 words, about 2 min