Zadania wzorowane na pytaniach z tego arkusza: te same umiejętności, format i punktacja, inne dane i kontekst. Treści arkusza IB nie publikujemy.
Dodaj cały arkusz do zestawu(i) Write a balanced equation for the reaction, including state symbols. (ii) Deduce what property of this reaction makes it possible to follow its rate by both methods. (iii) Magnesium carbonate was used in excess so that all of the acid would react.…
In Method 1 the flask containing 25.0 cm3 of the aqueous acid was put on the balance, which was then set to zero; 0.400 g of MgCO3 was added and the reading was noted every 20 seconds until the reaction had stopped. Each point is the mean of…
The student repeated the experiment using Method 2, with the same quantities of acid and solid. (i) Calculate the volume of gas that will have collected in the measuring cylinder once the reaction has finished, measured at T = 22 °C and…
The structure of lycopene is shown. To separate the lycopene, the filtered juice was shaken in a separating funnel with heptane, C7H16, and the mixture was left to form two immiscible layers, which were run into separate flasks. Predict which layer will…
Before the samples were measured, an absorption spectrum was recorded to find the best wavelength to use. (i) Describe the contents of the two solutions required to record the spectrum: the reference solution and the blank. (ii) The spectrum obtained is shown.…
The ascorbic acid in the juice was determined by titration with a standard solution of iodine, I2. The method is based on the following redox reaction: C6H8O6(aq) + I2(aq) → C6H6O6(aq) + 2 I−(aq) + 2 H+(aq) (i) Deduce the oxidizing agent in this…
The students wished to compare their result for ascorbic acid with the value given for pink grapefruit juice in a food-composition database. Suggest two aspects of the data or of the samples that the students must check before judging whether their value…
Complete the table for Trial 1 and so determine its Ka value. Use section 1 of the data booklet.
Ka was also calculated for Trials 2 and 3, and the experimental error was found for each, as shown in the table. Determine the experimental error for Trial 1, using a literature value of Ka = 1.35 × 10−5 for propanoic acid. If…
Comment on how the uncertainty of the pH probe affects the accuracy of the Ka values obtained.