Question

C. MOLECULES IN YOUR NAME Procedure: Use analytical balances and record all your masses to 0.001g. Show all you calculations with correct significant figures and units. 1. Record the mass of a chalk. 2. Write your full name (first, middle and last name) on the blackboard using this chall 3. One the same balance, record the mass of the chalk again. Complete the table below. Grey areas denote calculated values. A Mass before writing (g) 9.11 B Mass after writing (g) 9.042 c Mass used (@) 0.025 CAB a. Calculate the molar mass of the chalk. (Made of calcium carbonate. Caco 40.078+ 12.011 t 3115.999) = 100.08bu b. How many moles of chalk were in your name? 0.0259 x Imol Caco, 100.086 a -0.000249785 mol c. How many formula units of chalk were in your name? 2.4 x 10-4 units of 1 mol calor b.022 Xoom 4.0 mol callos d. What is the composition of each element in chalk? tra - 40.078 x 100.1 = 40.049% 100.086 - 12.011 " x 100 =/ 12.000 to 100.086 go o 3115.999) . (47.956d. 100 Opb CHEM10 - Laboratory Manual Lab 14 - Rancho & Chino Campus

Answer 1

in a part units entered is wrong so it would be gram/mol

in b part you have to convert answer into scientific form and that would be 2.49 X 10^-4

^{in d part you have to report percentage up to 2 significant figures so that will be % Ca = 40.04% , % C = 12.00% , %O = 47.95%}