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| Frage | Antworten |
| What is amount of substance measured in? | Moles (n) |
| How many particles are in a mole? | 6.02 x 10²³ (the Avogadro constant) |
| What is the equation for finding the number of moles, given the number of particles? |
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| What is the unit for molar mass? | gmol⁻¹ |
| TRUE OR FALSE: Molar mass has the same numerical value as the relative molecular/formula mass | TRUE |
| What is the equation linking number of moles to the mass of substance and molar mass? |
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| How do you find the number of moles, particles or atoms in a sample? | Multiply the number of moles in a sample by Avogadro's constant |
| Complete the sentences: If temperature and __________ stay the same, one mole of any gas always has the same _________ - this is known as the molar ______ __________ (dm³mol⁻¹). At room temperature and pressure (______k, _____kPa), the molar gas volume is ____ dm³mol⁻¹ (or __________ cm³mol⁻¹) | If temperature and PRESSURE stay the same, one mole of any gas always has the same VOLUME - this is known as the molar GAS VOLUME (dm³mol⁻¹). At room temperature and pressure (298k, 100kPa), the molar gas volume is 24 dm³mol⁻¹ (or 24,000 cm³mol⁻¹) |
| What is the equation linking number of moles and volume of a gas? |
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| What is the ideal gas equation? | pV = nRT p = pressure (Pa) T = temperature (K) n = moles R = gas constant (JK⁻¹mol) V = volume (m³) |
| What is the conversion between kPa and Pa? |
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| What is the conversion between °C and K? |
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| What is the conversion between cm³ and dm³? |
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| What is the conversion between cm³ and m³? |
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| What is the conversion between m³ and dm³? |
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| Complete the sentence: The concentration of a solution is how many ______ (or how many ______) of something are dissolved per 1dm³ of solution in moldm⁻³ (or ________). | The concentration of a solution is how many MOLES (or how many GRAMS) of something are dissolved per 1dm³ of solution in moldm⁻³ (or gdm⁻³) |
| What is the equation that links number of moles with concentration and volume? |
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| What is an empirical formula? | The smallest whole number ratio of atoms of each element in a compound |
| What is a molecular formula? | The actual numbers of atoms of each type of element in a molecule |
| How do you find the molecular formula given the empirical formula and molecular mass? | 1. Find empirical mass 2. Divide molecular mass by empirical mass 3. Multiply empirical formula by that number (step 2) |
| What are the two ways of calculating empirical formulas? | From experimental data From percentage composition |
| Outline how the empirical formula is calculated using experimental data | 1. Work out how many moles of each product has been made 2. Use moles of each product to work out how many moles of each atom you started with 3. Write down ratio of moles present at the start 4. Divide by the smallest number of moles to get a whole number ratio |
| What is meant by 'conservation of mass'? | Mass of products = mass of reactants |
| Outline how the empirical formula is calculated using percentage compositions | 1. Divide percentages by molecular mass 2. Divide by the smallest number of moles to get a whole number ratio |
| Complete the sentences: The water in a lattice is called ________ _____ _____________. A solid salt containing water of crystallisation is ___________. A salt is ______________ if it doesn't contain water of crystallisation. | The water in a lattice is called WATER OF CRYSTALLISATION. A solid salt containing water of crystallisation is HYDRATED. A salt is ANHYDROUS if it doesn't contain water of crystallisation. |
| Outline the method for finding the formula of hydrated salts from experimental data | 1. Find mass of water lost by taking the mass of anhydrous salt away from mass of hydrated salt 2. Find number of moles of water lost 3. Work out mole ratios of anhydrous salt : moles of water 4. Scale up/down so the ratio is 1:n |
| What is theoretical yield? | The theoretical yield is the mass of product that should be formed in a chemical reaction |
| What is the assumption made with theoretical yield? | No chemicals are 'lost' |
| The actual mass/yield will always be less than the theoretical yield. Why? | Not all chemicals react fully Some chemicals are 'lost' (between transfers) |
| What is the equation for percentage yield? |
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| What is atom economy? | A measure of the proportion of reactant atoms that become part of the desired product in the balanced chemical equation |
| What is the equation for atom economy? |
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| TRUE OR FALSE: In addition reactions, the atom economy is always 100% | TRUE The reactants combine to form a single product so no atoms are wasted |
| TRUE OR FALSE: In substitution reactions, atom economy can sometimes be 100% | FALSE A substitution reaction results in more than one product being formed so the atom economy is always LESS THAN 100% |
| In industry, why are low atom economies bad? | Less sustainable Lots of waste product (costs money to separate desired from waste, and also to dispose of waste safely) Reactants are expensive |
| In industry, what could be done to waste products (apart from disposal)? | Sold Used for something else |
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