7.1. The characteristic properties of acids and bases
A subsection of Chemistry, 5070, through 7. Acids, bases and salts
Listing 10 of 80 questions
Aqueous hydrogen peroxide decomposes when heated to form oxygen. 2H2O2O2+ 2H2OA 35.0 cm3 sample of 0.266 mol / dm3 H2O2 is completely decomposed. Calculate the volume of oxygen formed, measured at room temperature and pressure. Give your answer to two significant figures. volume of oxygen = dm3 Describe and explain the effect of decreasing the temperature on the rate of this reaction. Describe and explain the effect of increasing the concentration of hydrogen peroxide on the rate of this reaction. A sample of aqueous hydrogen peroxide has a pH of 5.5. State which ion is responsible for this pH value. A pH meter is used to measure the pH of an aqueous solution. Describe one other way to measure the pH of an aqueous solution.
5070_s24_qp_22
THEORY
2024
Paper 2, Variant 2
View
Ethanoic acid, CH3COOH, is a weak acid. What is the meaning of the term weak when applied to acids? Ethanoic acid is solid at 16.0 °C. Describe the arrangement and movement of the particles in a solid. arrangement movement The melting point of ethanoic acid is 16.7 °C. The boiling point of ethanoic acid is 118.0 °C. Deduce the physical state of ethanoic acid at 130.0 °C. Explain your answer. The equation for the reaction of ethanoic acid with sodium carbonate is shown. 2CH3COOH + Na2CO3 2CH3COONa + CO2 + H2O A student added 3.18 g of sodium carbonate to 224 cm3 of 0.250 mol / dm3 ethanoic acid. Show by calculation that sodium carbonate is in excess. Calcium reacts with ethanoic acid. The products are calcium ethanoate and hydrogen. Construct the equation for this reaction. Ethanoic acid reacts with butanol, C4H9OH, to produce an ester. Name the ester formed when ethanoic acid reacts with butanol. Draw the structure of this ester.
5070_w19_qp_21
THEORY
2019
Paper 2, Variant 1
View
Methanoic acid and ethanoic acid are weak acids. What does the term weak mean, when applied to acids? Methanoic acid, HCO2H, reacts with magnesium powder. Construct the equation for this reaction. State and explain how the rate of this reaction changes when the experiment is repeated using a piece of magnesium ribbon with the same mass as the powder. All other conditions stay the same. Include in your answer ideas about collisions between particles. Methanoic acid reacts with propanol, C3H7OH, to form an ester. Name and draw the structure of this ester, showing all of the atoms and all of the bonds. name structure Ethanoic acid is present in vinegar. Name the organic compound which is converted to ethanoic acid when vinegar is made. What type of chemical reaction is this? The table shows some properties of four carboxylic acids. carboxylic acid formula density in g / cm3 boiling point in °C methanoic acid HCO2H 1.22 ethanoic acid CH3CO2H propanoic acid C2H5CO2H 0.99 butanoic acid C3H7CO2H 0.96 Predict the density of ethanoic acid. g / cm3 Describe and explain the change in the boiling point as the number of carbon atoms in a molecule increases.
5070_w20_qp_22
THEORY
2020
Paper 2, Variant 2
View
The structure of an organic compound, T, is shown. H H H C CH2OH C Deduce the molecular formula of compound T. Compound T is a colourless liquid. State the colour change when excess compound T is added to aqueous bromine. from to Compound T can be oxidised to a carboxylic acid. Suggest a suitable oxidising agent for this reaction. Compound T can be polymerised. Draw the partial structure of the polymer of compound T. Show two repeat units. Compound T reacts with methanoic acid, HCOOH, to form an ester. Complete the structure of this ester to show all the atoms and all the bonds. H H H C C H H C C Methanoic acid is a weak acid. Hydrochloric acid is a strong acid. Give the formula of the positive ion that is present in all acids. Explain why the rate of reaction of 1.0 mol / dm3 methanoic acid with magnesium is less than the rate of reaction of 1.0 mol / dm3 hydrochloric acid with magnesium. Construct the equation for the reaction of methanoic acid with magnesium.
5070_w21_qp_22
THEORY
2021
Paper 2, Variant 2
View
Questions Discovered
80