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You have taken measure four times.To demonstrate that your measurement is repeatable ,is it more desirable that there is a low standard deviation or high standard deviation?
Calculate standard deviation using Bessel correction of the three values given below
21
22
23
how many grams of silver iodide, AgI, are produced from 55.3
55.3 g of calcium iodide, CaI2?
An unknown element (Y) is a nonmetal and has a valence electron configuration of ns²np4. (i) How many valence electrons does this element have? (ii) What is the formula of the compound this element would form with potassium? (iii) Would this element have a larger or smaller radius than barium? (iv) Would this element have a greater or smaller ionization energy than fluorine?
At what temperature will 4.15g of CO2 exert a pressure of 855 mmHg at a volume of 650 ml? (make sure to turn grams into moles)
Enter the electron configuration for Ne
Calculate the volume of 2.30 moles of gas exerting a pressure of 2.80 atm at 155°C.
A. Calculate the pH of a buffer made from 0.28 M HNO2 and 0.23
M NO2-. The ka for HNO2 is 4.6 x 10-4.
B. What is the pH of the solution containing 0.20 M NH3 and 0.15
M NHACI?
A. Calculate the pH of a buffer made from 0.28 M HNO2 and 0.23
M NO2-. The ka for HNO2 is 4.6 x 10-4.
The concentration of ethanoic acid in vinegar was measured as follows: A 50 cm3 sample of vinegar was diluted to 500 cm3 using deionised water. The diluted solution was titrated against 25 cm3 portions of a standard 0.12 M sodium hydroxide solution, using a suitable indicator. Titration reaction: CH3COOH(aq) + NaOH(aq) → CH3COONa(aq) + H2O(aq) After carrying out a number of accurate titrations of the diluted solution of ethanoic acid, the mean titration figure was found to be 20.5 cm3 . a) Calculate the concentration of ethanoic acid in the diluted vinegar solution in moles per liter.
