Citric Acid Essay Example for Free

Citric Acid Essay Introduction Soft drinks contain acid and sugar. These substances contribute to tooth decay and therefore are a cause for concern. In the first part of the investigation well measure the acidity in blackcurrant juice. Labels on black currant juice drinks usually state citric acid is present in the drink, but it doesnt give you the amount of how much it contains. Dilutable soft drinks contain between 0. 15 2. 5% of citric acid research by The British Drinks Association and therefore the second part of the experiment would be to determine the concentrations of blackcurrant juice in the diluted samples. Investigation 1: Measure the acidity of the blackcurrant juice drink In order to measure the acidity of the blackcurrant juice, Ill titrate black current juice with 0. 1mol of sodium hydroxide and use a pH meter to measure its pH. Technique The technique of this experiment is titration. It is a method of chemical analysis, which is used to determine the volume of concentration needed to react with an unknown solution. Equipments needed for titration: Burette   Conical Flask   Clamp Technique of using titration method: The measurement on the burette (cm3) tells you how much solution you have poured into the substance. This is useful to find the amount of solution needed to balance with the substance. At the end of the burette, there is a small tap that allows you to control the amount of solution needed to pour into the substance. It is important to be accurate on the amount you want to put in. Therefore, right timing and quick reaction is the key skill to this experiment. There are two ways of measuring the pH: pH indicator and pH meter. pH Indicator: A pH indicator is a chemical compound. It shows the pH changes in the substance by changing its colour when added. Different indicators have different colour. They only change its colour when a certain pH is reached. pH meter: A pH meter is an electronic machine used to measure the pH in liquids. It has a special measuring probe called the glass electrode connected to the electronic meter. It will then measure and display the pH reading. Because the black current juice is darkly coloured, therefore pH indicator would not be the most suitable method for this experiment. Im going to use a pH meter for this experiment. The Science Many of the soft drinks contain acids. It is use to balance the sweetness of the sugar present in the drinks. Citric Acid is one of the most common acid uses in soft drinks. Soft drink Blackcurrant juice contains: Water, Sugar, Glucose Fructose Syrup (from wheat and maize), Blackcurrant Juice from Concentrate (4%), Citric Acid, Vitamin C, Preservatives (Sodium Benzoate, Sodium Bisulphate) and Colour (Anthocyanins) Citric Acid Citric Acid is an organic acid. We can find it from citrus fruits such as lemon and orange. It is added to soft drinks to create an acidic taste (sourness). Citric Acid also helps preserve drinks from micro-organism because of its acidity. Micro-organism can only grow and multiply in neutral condition. The reaction between Sodium Hydroxide and Citric acid: The following equation shows the reaction of whats happening during the neutralisation reaction between Citric Acid and Sodium Hydroxide: Citric Acid + Sodium Hydroxide Sodium citrate + Water C6H8O7 + 3NaOH C6H8O7Na3+ 3H2O From the equation above we have worked out 1 mole of citric acid reacts with 3 moles of sodium hydroxide (1:3 ratios). Graph Demonstration. Strong and Weak Acids Acids are vary in strength. The strength of an acid is based on the number of Hydrogen ions in the atom. Strong acids: Strong acids have a strong proclivity to donate Hydrogen+ ions. All of the strong acids such as hydrochloric acid, Sulphric acid and Nitric acid are all 100% ionised in water. This mean all the strong acid would dissolve the reaction is fully complete and no unreacted substance remains in the solution. Weak acids: Weak acids have a weak tendency to donate Hydrogen+ ions. The donation of hydrogen+ ions does not dissociate completely.