11.7. Carboxylic acids
A subsection of Chemistry, 5070, through 11. Organic chemistry
Listing 10 of 61 questions
The table shows some properties of five alcohols. alcohol formula density in g / cm3 boiling point in °C methanol CH3OH 0.791 ethanol C2H5OH 0.789 propanol C3H7OH 0.803 butanol C4H9OH 0.810 pentanol C5H11OH 0.814 What is the general trend in the density of the alcohols as the number of carbon atoms in a molecule increases? Describe and explain the change in the boiling point of the alcohols as the number of carbon atoms in a molecule increases. Ethanol, C2H5OH, reacts with butanoic acid, C3H7CO2H, to produce an ester. A few drops of a strong acid are added to catalyse the reaction. What does the term strong mean, when applied to acids? Name and draw the structure of the ester produced when ethanol reacts with butanoic acid, showing all of the atoms and all of the bonds. name structure Ethanol can be oxidised to ethanoic acid in the laboratory. State the reagents and conditions used in this reaction. reagent conditions Concentrated ethanoic acid, CH3CO2H, reacts with calcium. The products are calcium ethanoate and hydrogen. Construct the equation for this reaction. State and explain how the rate of this reaction changes when the experiment is repeated using dilute ethanoic acid. All other conditions stay the same. Include in your answer ideas about collisions between particles.
5070_w20_qp_21
THEORY
2020
Paper 2, Variant 1
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Ethanoic acid is manufactured from methanol. CH3OH+ COCH3COOHThe forward reaction is exothermic. Predict and explain the effect, if any, on the position of equilibrium when the pressure is decreased and the temperature remains constant. Predict and explain the effect, if any, on the position of equilibrium when the temperature is decreased and the pressure remains constant. Ethanoic acid can be produced by bacterial oxidation. Describe one other method of making ethanoic acid by oxidising an alcohol other than methanol. name of alcohol name of oxidising agent Ethanoic acid reacts with propan‑1‑ol, CH3CH2CH2OH, to produce an ester. Name the ester and draw its displayed formula. name displayed formula
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THEORY
2023
Paper 2, Variant 1
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The structure of ethyl propenoate is shown. C H C H C O C O H H H C H H H Circle the atoms in the structure that show that ethyl propenoate is an ester. Aqueous bromine is shaken with a sample of ethyl propenoate. Explain, in terms of the structure of ethyl propenoate, why the aqueous bromine turns colourless. Ethyl propenoate is prepared by the reversible reaction between a carboxylic acid and an alcohol, as shown. C H C H C O H O H C H C H C O C O H H H C H H O H H H C O C H H H H H H + + A mixture of the carboxylic acid and the alcohol is allowed to reach equilibrium. Name the alcohol used in the reaction. The reaction uses an acid catalyst. State the effect of this catalyst on the position of equilibrium. The concentration of the alcohol is increased. Describe and explain what happens to the position of equilibrium. In an experiment 10.8 g of the carboxylic acid is reacted with an excess of the alcohol. The experimental yield of ethyl propenoate is 9.45 g. [The relative formula mass of the carboxylic acid is 72.] Show that the maximum possible yield of ethyl propenoate is 15.0 g. Calculate the percentage yield of ethyl propenoate in this experiment. % yield
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THEORY
2021
Paper 2, Variant 2
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