12. Experimental techniques and chemical analysis
A section of Chemistry, 0620
Listing 10 of 677 questions
Intracellular fluid is the solution between the cells in the human body. Table 2.1 shows the masses, in mg, of some ions in 100 cm3 of intracellular fluid. Table 2.1 name of ion formula of ion mass of ion in 100 cm3 of intracellular fluid / mg calcium Ca2+ chloride Cl – hydrogencarbonate HCO3 – phosphate PO4 3– magnesium Mg2+ potassium K+ sodium Na+ sulfate SO4 2– Answer these questions using information from Table 2.1. Name the positive ion that is present in the lowest concentration. Name the ion that contains an element in Group IV of the Periodic Table. Describe a test for sulfate ions. test observations  Small amounts of ammonium ions and chloride ions are formed in some cells of the body. State the formula of the compound formed from ammonium ions and chloride ions. Choose from the list the salt that is insoluble in water. Tick (✓) one box. copper(nitrate lead(chloride potassium nitrate sodium chloride  Table 2.2 shows some properties of the Group I metals. Table 2.2 metal hardness / MPa observations on reaction with water lithium 5.0 bubbles form very slowly and no flame sodium 0.69 bubbles form very slowly and no flame potassium bubbles form very rapidly and flame rubidium 0.22 Use the information in Table 2.2 to: ● predict the hardness of potassium ● describe the observations when rubidium reacts with water.  Sodium reacts with hydrogen to produce sodium hydride, NaH. Complete the symbol equation for this reaction. 2Na + → NaH 
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THEORY
2024
Paper 3, Variant 3
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Barium sulfate, BaSO4, is an insoluble salt and is made by precipitation. Name two aqueous solutions that produce a precipitate of barium sulfate when they are mixed.  Describe how to produce a pure sample of barium sulfate from the mixture of aqueous solutions in . Write an ionic equation for the precipitation reaction which produces barium sulfate. Include state symbols. Soluble salts are made from dilute acids. Name the dilute acid and one other substance that react together to make copper(sulfate. dilute acid other substance  Nitrates decompose when they are heated. When hydrated copper(nitrate is heated, oxygen gas is produced. Describe a test for oxygen. test observations  Complete the equation for the decomposition of hydrated copper(nitrate. 2Cu(NO3)2•3H2O → CuO + NO2 + O2 + H2O Hydrated zinc sulfate gives off water when it is heated. ZnSO4•xH2O→ ZnSO4+ xH2OA student does an experiment to determine the value of x in ZnSO4•xH2O. step 1 The student weighs a sample of hydrated zinc sulfate. step 2 The student heats the sample of hydrated zinc sulfate. step 3 The student weighs the solid after heating. step 4 The student repeats step 2 and step 3 until the mass of solid after heating is constant. State why the student does step 4. In an experiment, 0.574 g of ZnSO4•xH2O is heated until the mass is constant. The mass of ZnSO4 that remains is 0.322 g. [Mr: ZnSO4, 161; H2O, 18] Determine the value of x using the following steps. ● Calculate the number of moles of ZnSO4 remaining.  mol ● Calculate the mass of H2O given off.  g ● Calculate the number of moles of H2O given off.  mol ● Determine the value of x.  x =  
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THEORY
2024
Paper 4, Variant 3
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