Supplemental Instruction
Iowa State University / Leader: / Kia
Course: / CHEM 177
Instructor: / Anand
Date: / January 31st, 2017
From last time
1. The average human requires 120.0 grams of glucose (C6H12O6) per day. How many grams of CO2(in the photosynthesis reaction) are required for this amount of glucose? The photosynthetic reaction is:
6 CO2+ 6 H2O ---> C6H12O6+ 6 O2
Concept Check
Determine how many tootsie rolls your group can make with the given jolly ranchers following this balanced equation. (W=watermelon, A=apple, C=cherry, G=grape, T=tootsie roll)
W + A + 2 C + G à 2 T
Practice problems
1. Which of the following is the limiting reagent if three moles of H2O and eight moles of NO2 are available in the reaction: 3 NO2(g) + H2O(l) à 2 HNO3(l) + NO(g)
2. Given the following equation determine how many grams of CO2 are formed when 10.05 g of H2C2O4 and 26.72 g of KMnO4 are mixed together?
3 H2C2O4 + 2 KMnO4 à 2 H2O + 6 CO2 + 2 MnO2 + 2 KOH
3. An unknown compound [Molar mass 130.0 g/mol] is found to contain only carbon, nitrogen and hydrogen. A 12.50 gram sample of this compound was analyzed to contain 73.85% carbon, 21.54% nitrogen and 4.61 % Hydrogen. What is the empirical formula and molecular formula of this compound?
4. Menthol, the substance we can smell in mentholated cough drops, is composed of C, H, and O. A 0.1005 g sample of menthol is combusted, producing 0.2829 g of CO2 and 0.1159 g of H2O. What is the empirical formula for menthol? If menthol has a molar mass of 156 g/mol, what is the molecular formula?
5. The element lead (Pb) consists of four naturally occurring isotopes with atomic masses 203.97663, 205.97444, 206.97587, and 207.97663 amu. The relative abundances of these four isotopes are 1.4, 24.1, 22.1, and 52.4% respectively. From these data, calculate the atomic weight of lead.
Exit Slip – Exam Review/Thursday Topics