lab#3 _9_10_11 - number of moles of H 2 will be thrown off....

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9 The reason to wait till the end of the reaction to take the measurement because: 1. To be sure of the reaction between magnesium and hydrochloric acid is completely finished. As an outcome we can find the correct number of moles of the H 2(gas) transformed using the moles mass conservation theorem. The number of moles affects the R value we are trying to calculate. 2. We allowed the reaction to cool down so that the temperature of the gases became the same temperature as the room which also affects the pressure in the burette. The pressure also affects the R value that we are trying to calculate. 10 If some magnesium remains after the reaction is completed then our calculation of the
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Unformatted text preview: number of moles of H 2 will be thrown off. n (Mg) decreases therefore n (H2) decreases (conservation of moles n (Mg) = n (H2) ) the equation for calculating R value is, R = PV/nT. R and n are inversely proportional to each other. Therefore n value decreases, R value increases. 11 Ignoring the partial measurement of pressure of vapour water in the burette P (H2O) will affect the measured value of R because: P (H2) = P (gases)- P (H2O) ignoring P (H2O) : P (H2O) = 0; P (H2) = P (gases) therefore the pressure value of H 2 : P (H2) will increase. We know: R = PV/nT R and P are proportional to each other. Therefore if P (H2) increases therefore R value increases....
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This note was uploaded on 11/11/2010 for the course CHEMISTRY CHEM1800 taught by Professor Krista during the Winter '10 term at UOIT.

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