CHE11S Name:, Tear this page out of your laboratory manual and submit it to your
ID: 1031143 • Letter: C
Question
CHE11S Name:, Tear this page out of your laboratory manual and submit it to your TA with your answers. B. Post-Lab Assessment Questions: (32 pts) 1. (4 pts) Given that zinc reacts with iodine in the fixed mass ratio of 1 gram of zinc 3.88 grams of iodine, how many grams of iodine are required to completely react with 4.2 grams of zinc? You must show your work to get credit 2. Consider the chemical reaction that that occurs when calcium chloride (CaCl2) reacts with sodium phosphate (NasPO4). a) (4 pts) Write the balanced chemical equation. b) (4 pts) Usin g the data you obtained today determine the fixed mass ratio for the reaction of CaCl2 with NasPO. Represent this ratio as 1 g of CaClz to of NasPO4 grams 3. Given that a cup of coffee costs 90 cents and you have 100 grams each of nickels, quarters and dimes, if a nickel weighs 5.00 g, a quarter weighs 5.55 g and a dime weighs 2.22 g a) (8 pts) What is the maximum number of cups of coffee can you buy with your change? b) (2 pts) How much money will you have left over? 4. (10 pts) The law of mass conservation is another fundamental law in chemistry. This law states that matter can neither be created nor destroyed, which means that in a chemical reaction where all of the reactant is converted into product, the mass of reactant that reacts must be exactly equal to the mass of product produced. Next week you are going to test the law of mass conservation. To do this you will need to design your own experiment a) Consider the 2 precipitation reactions you have already studied this semester. b) Think about an experimental procedure that you can use next week. Rememb that you are trying to collect data that can be used to illustrate the law of ma conservation. c)Contemplate how you might visually represent this data in the form of a graph. (i) What are the variables that you might need to plot. (ii) How would your choice of graph illustrate the law of mass conservation.Explanation / Answer
I am solving the first two problems Q1 and Q2( since Q2 contains two sub-parts) as per Chegg guidelines. Post multiple question to get the remaining answer
1)
The reaction happening will be
Zn(s) + I2(s) -------- ZnI2(s)
1 gram of zinc reacts with 3.88g of I2
Mass of I2 required for 4.2g of zinc = 4.2g zinc * 3.88g I2/1g zinc = 16.296 grams
Since mass of zinc is with two significant digits, hence the final answer will be 16.3 grams
2)
a) The balanced reaction happening will be
3CaCl2(aq) + 2Na3PO4(aq) -------- Ca3(PO4)2(s) + 6NaCl(aq)
Molar mass of CaCl2 = 40 + 2 * 35.5 = 111 gm/mol
Molar mass of Na3PO4 = 3 * 23 + 16 + 4 * 16 = 149 gm/mol
3 moles of CaCl2 requires 2 moles of Na3PO4
Moles of CaCl2 = 1/111
Moles of Na3PO4 = 1/111 * 2/3
Mass of Na3PO4 required = 1/111 * 2/3 * 149 = 0.894 grams