e10c9b1f-bdae-4934-b896-4292a13154fb","label":"a","content":"Calculate the **mass** of oxygen made when \$0.65\$ moles of calcium nitrate decomposes.\nRelative atomic mass (\$A_{\\text{r}}\$): \$\\text{O} = 16.0\$.\n\nMass of oxygen = \$\\text{........................................................................... g}\$","markscheme":"- Identifies the stoichiometric ratio between $\\text{Ca(NO}_3)_2$ and $\\text{O}_2$ as $2 : 1$, giving $\\text{moles of O}_2 = \\frac{0.65}{2} = 0.325\\text{ mol}$ M1\n- Calculates the relative molecular mass of $\\text{O}_2$ as $32.0\\text{ g/mol}$ B1\n- Calculates the mass of $\\text{O}_2 = 0.325 \\times 32.0 = 10.4\\text{ g}$ A1","marks":3,"order":0,"markingRubric":null,"explanation":null,"options":[]},{"id":"1e161d66-7d20-4083-bbc9-83cbabe3de43","label":"b","content":"Calculate how many **molecules** of nitrogen dioxide, \$\\text{NO}_2\$, are produced from \$0.65\$ moles of calcium nitrate.\nThe Avogadro constant is \$6.02 \\times 10^{23}\$.\nGive your answer to **3** significant figures.\n\nNumber of molecules of \$\\text{NO}_2 = \\text{...........................................................................}\$","markscheme":"- Identifies the stoichiometric ratio between $\\text{Ca(NO}_3)_2$ and $\\text{NO}_2$ as $1 : 2$, giving $\\text{moles of NO}_2 = 0.65 \\times 2 = 1.30\\text{ mol}$ M1\n- Multiplies the number of moles by Avogadro's constant: $1.30 \\times (6.02 \\times 10^{23}) = 7.826 \\times 10^{23}$ M1\n- Gives the final answer rounded to 3 significant figures as $7.83 \\times 10^{23}$ A1","marks":3,"order":1,"markingRubric":null,"explanation":null,"options":[]},{"id":"94de39b5-92ff-4005-b67b-2266e5a45a2b","label":"c","content":"The neutralization of an acid with an alkali is an **exothermic** reaction.\nComplete the reaction profile for an exothermic reaction.\n\n![An incomplete reaction profile diagram with axes.](https://assets.mathsgenie.co.uk/aqa-qb/03b8287c-8a79-4664-b06a-11251195463f.png)\n\nInclude the labels:\n* products\n* activation energy\n* energy change of reaction","markscheme":"- Draws a profile curve starting at the level of the reactants, rising to a peak, and then falling to a horizontal line for the products that is lower than the reactants line M1\n- Labels the lower plateau as 'products' A1\n- Identifies the activation energy as an upward vertical arrow from the reactants line to the peak of the curve B1\n- Identifies the overall energy change of the reaction as a downward vertical arrow from the reactants line to the products line B1","marks":4,"order":2,"markingRubric":null,"explanation":null,"options":[]},{"id":"eaf6626d-e3a9-4a1a-9d46-b9fb83dcfc0a","label":"d","content":"Calcium nitrate is an ionic compound.\nExplain why calcium forms \$\\text{Ca}^{2+}\$ ions.","markscheme":"- Explains that calcium (in Group 2) has 2 electrons in its outer shell B1\n- Explains that it loses these 2 outer-shell electrons to achieve a stable, full outer energy level / noble gas configuration B1","marks":2,"order":3,"markingRubric":null,"explanation":null,"options":[]},{"id":"f379f765-6e58-4b5c-bed2-7b2720af7da0","label":"e","content":"A solution containing calcium ions reacts with a solution containing hydroxide ions.\nSolid calcium hydroxide is made.\nWrite the **balanced ionic** equation for this reaction.","markscheme":"- Writes the formula of the reactant ions as $\\text{Ca}^{2+}$ and $\\text{OH}^-$ M1\n- Writes the correct balanced ionic equation: $\\text{Ca}^{2+} + 2\\text{OH}^- \\rightarrow \\text{Ca(OH)}_2$ A1","marks":2,"order":4,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null}],"subjectCode":"gcse_chemistry__ocr","summaries":[{"id":"0327ccbe-025f-47d1-a798-31e8133c3d32","difficultyBand":"easy","calculatorUse":null},{"id":"04f479a4-02a4-456a-a18c-5570af6d448b","di

Monitoring chemical reactions

Question 32

Monitoring chemical reactions Questions

Monitoring chemical reactions

Question 32

Monitoring chemical reactions Questions