Question

15. Use the Ideal Gas Law and the answers to questions 12, 13 and 14 to calculate the number of moles of hydrogen gas present. R 0.0821 Leatm/mol K (watch sig figs.) 16. A student reacted 0.7655 g of chromium (at. wt - 51.996 g/mol) with exactly 1.566 g of chlorine (at. wt. - 35.453 g/mol). Convert both these masses to moles and determine the empirical formula (like AX) of the compound of Cr and CL SHOW YOUR WORK 17. In a chemical reaction, the substance which gets used up first (or runs out first) is called the (write in the correct words). 18. In a chemical reaction, the maximum amount of product which can be made when one of the starting materials is completely used up is called the (write in the correct words). 19. Select from the choices below the blanks to correctly complete the sentence: The equation which relates the light absorbed through a solution to the concentration of that solution is and it is called AC, AC Petit's Partition PV=nRT Tolmen's Law L=12 mc Beer's Law A==bC Lumens' Equation 20. In a certain titration, 25.00 mL of HCl reacted exactly with 32.36 mL of 0.1250 M NaOH. What is the concentration (M) of the HCI? (The reaction stoichiometry is 1:1) (watch sf)

Answer 1

16)

Moles of Cr = Mass/Molar mass = 0.7655/51.996 = 0.014722

Moles of Cl = 1.566/35.453 = 0.044171

Simplest mole ratio i.e. diving each moles with smallest number (0.014722)

Cr : Cl = (0.014722/0.014722) : (0.044171/0.014722)

Cr : Cl = 1 : 3

Thus, empirical formula is Cr1Cl3 = CrCl3 ....Answer

17)

Limiting Reagent - running out first

18)

Yield of reaction

19)

A = € b C and Beer's law

20)

M1 * V1 = M2 * V2

M1 * 25 = 0.1250 * 32.36

M1 = 0.1618 mol/L ....Answer

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