Zadanie 1a
Hydrochloric acid, HCl(aq), and hydroiodic acid, HI(aq), ionize completely in water, whereas propanoic acid, CH3CH2COOH(aq), ionizes only partly. 25.0 cm3 of 0.200 mol dm−3 HCl(aq) was titrated with sodium…
Molar concentration of solutions
Calculate concentration in mol dm⁻³ or g dm⁻³ from the amount of solute and the solution volume, rearrange to find moles or volume, handle dilutions, and convert between cm³ and dm³.
Tę umiejętność sprawdzają 32 zadania wzorowane na arkuszach IB z lat 2022–2026.
Zadania sprawdzające tę umiejętność: 32 Otwórz w wyszukiwarce z filtrami
Zadanie 1b
Potassium also forms compounds with polyatomic ions. 2 KOH(aq) + Cu(NO3)2(aq) → Cu(OH)2(s) + 2 KNO3(aq) (i) 30.0 cm3 of a 0.380 mol dm−3 potassium hydroxide, KOH, solution is mixed with 25.0 cm3 of a 0.310…
Zadanie 1a
Determine the mass of sodium thiosulfate pentahydrate, Na2S2O3 ⋅ 5 H2O, needed to prepare 250.0 cm3 of a 0.2000 mol dm−3 solution.
- Materiał graficzny
Zadanie 1b
Explain how the 0.2000 mol dm−3 solution is prepared in a volumetric flask from the weighed solid.
- Materiał graficzny
Zadanie 1c
Suggest how to prepare 100.0 cm3 of a 0.05000 mol dm−3 sodium thiosulfate solution from the 0.2000 mol dm−3 solution.
- Materiał graficzny
Zadanie 1a
Before use, the EDTA solution was standardized against a standard solution of Cu2+ ions. An accurately weighed piece of pure copper wire was dissolved in the minimum volume of concentrated nitric acid and the mixture was warmed gently until no more…
Zadanie 1b
Anhydrous copper(II) chloride, CuCl2, takes up water vapour from the air, so it cannot be weighed out accurately to make a standard solution. Suggest a laboratory procedure that would remove all of the absorbed water from a sample of solid CuCl2…
Zadanie 1d
For the AAS method, a series of standards of known concentration was prepared by diluting a stock solution of Cu2+ ions. The instrument was zeroed with deionized water and the absorbance of each standard was recorded. (i) Draw the line of best fit for…
- Materiał graficzny
Zadanie 2a
Describe how a standard aqueous solution of potassium manganate(VII) can be prepared from the solid.
Zadanie 2b
Describe the steps by which this standard solution is turned into a calibration curve for the colorimeter.
Zadanie 2c
Explain how the calibration curve is then used to determine the concentration of KMnO4 in a reaction mixture of unknown concentration.
Zadanie 3a
Draw a line of best fit on the graph, extrapolating it beyond the range of the data.
- Materiał graficzny
Zadanie 3b
State, in mathematical terms, how the absorbance of these solutions depends on their concentration.
- Materiał graficzny
Zadanie 3c
Deduce the equation that relates absorbance to concentration for these solutions, including the numerical value of the constant.
- Materiał graficzny
Zadanie 3d
Estimate the absorbance of a 0.400 mol dm−3 solution of nickel(II) sulfate.
- Materiał graficzny
Zadanie 1a
Calculate the mass of solid potassium hydroxide that has to be weighed out.
Zadanie 1b
Describe how the student should prepare this standard solution from the weighed solid using a 250.0 cm3 volumetric flask.
Zadanie 1c
The student pipetted 25.00 cm3 of the potassium hydroxide solution into a conical flask and titrated it with nitric acid, HNO3(aq), of concentration 0.1250 mol dm−3. The burette readings before and after the titration are…
- Tabela do uzupełnienia
- Materiał graficzny
Zadanie 1e
Explain why the potassium hydroxide solution has to be standardized before it is used in the titration. Assume that there are no systematic errors in the procedure.
Zadanie 4
4.06 g of hydrated magnesium chloride, MgCl2 ⋅ 6 H2O (Mr = 203), is dissolved in water to make 0.250 dm3 of solution. What is the concentration of chloride ions, in mol dm−3, in this solution? A. 0.0400 B. 0.0800 C.…
Zadanie 1c
A student compiles data on the solubility of bromine in water at different temperatures from several websites and textbooks. (i) Identify one problem that arises when the values from these sources are compared with one another. (ii) Each solubility is then…
- Tabela do uzupełnienia
Zadanie 1b
A 20.00 cm3 sample of a solution containing 1.21 g of HA is titrated with 0.500 mol dm−3 sodium hydroxide solution, NaOH(aq). Exactly 27.40 cm3 of the NaOH(aq) is required to neutralize the acid completely. Determine…
Zadanie 6b
The iodine number of a fat or oil is the mass, in grams, of iodine that reacts with 100 g of the fat or oil. It is a measure of the degree of unsaturation. A 3.50 g sample of peanut oil reacts completely with 65.5 cm3 of…
Zadanie 2c
The end point was reached after 3.0 ± 0.1 cm3 of titrant had been run in. (i) Calculate the percentage uncertainty in this titre. (ii) Suggest one change to the procedure that would lower the percentage uncertainty of a single titration, apart from…
Zadanie 3b
The concentration of dissolved oxygen in a sample of pond water was determined by the Winkler method. The reactions that take place are:…
Zadanie 4b
The concentration of copper(II) ions in a sample of pond water is determined with a colorimeter. The absorbance of standard solutions of known concentration is measured and a calibration curve is plotted. Sketch the typical shape of the calibration curve on…
- Materiał graficzny
Zadanie 5c
A volume of 21.6 cm3 of KOH(aq) neutralized 25.0 cm3 of the ethanoic acid solution. Determine the concentration of the ethanoic acid.
Zadanie 18a
Magnesium hydroxide is the active ingredient of some indigestion remedies, which neutralize excess hydrochloric acid in the stomach. (i) Write an equation for the reaction of magnesium hydroxide with hydrochloric acid. (ii) Calculate the mass, in g, of…
Zadanie 1
A student mixes 100 cm3 of 0.50 mol dm−3 calcium chloride solution with 150 cm3 of 1.00 mol dm−3 potassium chloride solution. What is the concentration of chloride ions, in mol dm−3, in…
Zadanie 1b
A 0.460 g piece of sodium was placed in 250.0 cm3 of water. (i) Calculate the molar concentration of the sodium hydroxide solution formed. Assume that the volume of the solution is 250.0 cm3. (ii) Calculate the volume of hydrogen gas…
Zadanie 2
Which sample contains the fewest moles of HBr? NA = 6.02 × 1023 mol−1. Molar volume of an ideal gas at STP = 22.7 dm3 mol−1. A. 0.647 g of HBr(g) B. 50.0 cm3 of…
Zadanie 2e
Methylamine is a gas that dissolves in water to form an alkaline solution: CH3NH2(aq) + H2O(l) ⇌ CH3NH3+(aq) + OH−(aq) (i) State the relationship between CH3NH3+ and CH3NH2 in terms of the Brønsted-Lowry theory. (ii) A sample of…