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An investigation to find out what the effect of changing the concentration of calcium ions has on the rate of coagulation of milk

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Introduction

An investigation to find out what the effect of changing the concentration of calcium ions has on the rate of coagulation of milk Introduction: I am going to find out what the effect of changing the concentration of calcium ions, using calcium chloride has on the rate of the coagulation of milk. Background: Milk contains 290mg of calcium in every 8 ounces of milk. The function of calcium is that it helps maintain and build strong bones and teeth. However when the enzyme rennin is used on it, it can cause the milk to coagulate (clot). This process can be used to make cottage cheese as the rennin helps separate the curds from the milk Rennin is an enzyme which is used in the coagulation of milk. It can be used to catalyse the conversion of a protein called casein, which is found in the milk. This is converted into para-casein by removing a glycopeptides from the casein. The para - casein further coagulates in the presence of the calcium ions to form white curds. This can then be separated from the whey to make cottage cheese. However in the experiment which I am carrying out, when the milk starts to coagulate flecks are first formed.� � http://www.glue.umd.edu/~nsw/ench485/lab1.htm 200 Prediction: My prediction is that when the concentration of calcium ions in calcium chloride is increased, then the rate of coagulation of milk will also increase. ...read more.

Middle

600 These two experiments mean that in the real experiment I will use the concentrations 1, 0.4, 0.1, 0.01 and 0.001, and I will use 1cm� of rennin and a temperature of 40 �C. I will still use a pH of 7 and use 1cm� of sodium citrate and 10cm� of milk Making the concentrations: End concentration (mol dm�) Volume of calcium chloride (cm�) Volume of distilled water (cm�) 1 1.00 0.00 0.4 0.40 0.60 0.1 0.10 0.90 0.01* 0.10 of 0.1moldm� 0.90 0.001* 0.10 of 0.01moldm� 0.90 *For the 0.01 moldm� you have to add 0.1cm� of 0.1 moldm� and 0.9cm� of distilled water. For the 0.001 moldm� add 0.1 cm� of 0.01 moldm� and 0.9 cm� of distilled water. Converting Time Taken to rate of coagulation: Relative rate of coagulation = 1000 t Apparatus list: Item What it is used for Reason for choice Graduated pipette To measure the volume of solutions Can be used to measure smaller volumes such as that of the rennin, sodium citrate and calcium chloride. This will lower the percentage error making the experiment more reliable and accurate Burette Used to measure larger volumes Accurate to �2.5 ml and can be used to measure the volume of the milk. This is so that the percentage error can be lowered making the experiment more reliable and accurate. Thermometer Used the measure the temperature of the solution Accurate to �0.2 �C and can be used to measure the temperature of the solution, such as the milk along with sodium citrate. ...read more.

Conclusion

800 Method: * Using the apparatus listed, measure out 10 cm� of whole fat milk using a burette, into a beaker. Put a microscope slide into it * Add 1 cm� of sodium citrate to this using a 1 cm� graduated pipette * Shake thoroughly so that all the calcium ions in the milk can be removed * Add 1 cm� of rennin using another 1cm� graduated pipette into a test tube. Place this in the test tube rack * Add 1cm� of calcium chloride to another test tube using another graduated pipette and place that in the test tube rack * Place the beaker and test tube rack in the thermostatically controlled water bath, set to 40�C for 10 minutes * After this, add the rennin and the calcium chloride at the same time, and start the stop clock * Every 5 seconds check for any flecks * Record the time in a table * Convert the time taken into rate of reaction using the formula * Carry out the same procedure for each concentration three times * If there are any anomalies in the results, repeat that concentration again, so that you end up with three similar results for each concentration * Take the average for each concentration and plot it on a graph 1000 Results Table: Concentration of Calcium Chloride Time taken 1 (s) Rate of reaction 1 (s��) Time taken 2 (s) Rate of reaction 2 (s��) Time taken 3 (s) Rate of reaction 3 (s��) 1 0.4 0.1 0.01 0.001 ?? ?? ?? ?? 1 ...read more.

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