Week 7 Pre Lab Empirical Formula Questions PDF

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Assignment For Week 7...

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Empirical Formula of Copper Chloride Pre-Lab Questions

Due: Week 7, Friday March 12th BY 11:59 PM.

1. (2 Points) Hermione Granger is a diligent student. She wants to know what the empirical formula for C4 H10 is. What is it? A) C4 H4 B) CH2 C) CH D) C2 H5 E) C2 H2 2. (2 Points) Now that Hermione understands empirical formulas she wants to teach Harry and Ron. What is the empirical formula for dibromoethane: C2 H4 Br2 A) C2 H4 Br B) CH2 Br2 C) CH2 Br D) C2 H2 Br2 E) CHBr 3. (2 Points) Severus Snape explains that if you have the molar mass of a compound and the empirical formula of a compound you can determine the molecular formula of a compound. Suppose you have a compound which has an empirical formula of C2 H3 O and molar mass of 86 g/mol. What is the compounds molecular formula? A) C2 H4 O B) C2 H5 O C) C2 H3 O D) C4 H6 O2 E) C6 H9 O3 4. (2 Points) A compound is found to contain only 24.5 g nitrogen and 70.0 g oxygen. What is the compounds empirical formula. A) NO B) NO3 C) N2 O3 D) NO4 E) N2 O5 5. (2 Points) Albus Dumbledore provides his students with a sample of 19.3 g of sodium sulfate. How many oxygen atoms are in this sample? A) 1.24*1023 O atoms

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B) 4.97*1023 O atoms C) 2.41*1024 O atoms D) 3.27*1023 O atoms E) 1.17*1025 O atoms 6. (2 Points) Now that we understand the basics, Snape wants you to consider the following UNBALANCED equation: Al(s)+HCl(aq) → AlCl3 (aq)+H2 (g). Assume you have plenty of HCl and 6.0 mol of Al. How many moles of H2 are formed? Express your answer in moles. 7. (2 Points) Let’s try one more but add the theoretical yield concept. Consider the following UNBALANCED equation: NO(g) + H2 (g) → NH3 (g) + H2 O(g) If you start with 89.3 g NO(g) and 28.6 g H2 (g), find the theoretical yield of ammonia. Express your answer in grams. 8. (2 Points) Ron Weasley isn’t the best experimentalist. After an experiment he ends up with only 3.10 g of product. However, the same reaction has is a theoretical yield of 3.50 grams of product. What is the percent yield? 9. (2 Points) In attempts to lift Ron’s spirits, Dumbledore asks him a fairly easy question: calculate the mass percent composition of carbon in C2 H5 Cl. Prof. Vitarelli thinks you should try this also. 10. (2 Points) Ron was able to get the previous problem right! Hopefully so were you. Now, as a small extension to the previous problem Snape asks everyone to calculate the mass of chlorine in 21 kg of C2 F3 Cl3 . Express your answer in kg. 11 (2 points) Looking at the bottom of her tea cup, Prof. Trelawney suddenly has a revelation! She knows one of the previous exam questions! She bursts into the class and and yells: Analysis of a sample is finds it contains 15.0% of species X, by mass, 75.0% of species Y, and 10.0% of species Z, by mass. The molar mass of species X is 45.0 g/mol, the molar mass of species Y is 150. g/mol, and the molar mass of species Z is 30.0 g/mol. If the molar mass of the sample is 1200 g/mol, what is the molecular formula of the sample? Prof. Vitarelli frowns at her disapprovingly. A. X4 Y6 Z4 B. X4 Y5 Z4 C. X3 Y6 Z3 D. X4 Y4 Z4 E. X2 Y5 Z2 12 (2 points) As a final problem for the week Snape thinks we should incorporate something from a previous week, hydrates perhaps. Suppose we have a compound that is 4.330 % Li, 22.10 % Cl, 39.89 % O, and 33.69 % H2 O. What is the compounds formula? A. LiClO4 · 3 H2 O B. LiCl2 O3 · 5 H2 O C. Li2 Cl2 O3 · 5 H2 O D. Li2 Cl2 O3 · 4 H2 O E. LiClO3 · 4 H2 O...