17 Grade 12 chemistry questions.
Express the answer to the correct number of significant digits with the
26. 10.51 g
+ 3.89 g
27. (20.95 s)(6.78x10^4 m/s) =
17.1 g-5.09 g (subtraction)
(6.626 × 10-34 J·s)(3.00 × 108 m/s) =
9.72 × 106 m
37. A container of mass 25.00 g is found to have a total mass of 45.22 g when a sample of potassium nitrate is added. Determine the number of moles of potassium nitrate added to the container.
38. A rock is found to have a mass of 33.8 g. When placed in a graduated cylinder containing 40.0 mL of water, the level of the water is observed to rise to 43.6 mL. Find the density of the rock.
39. What are the steps for obtaining the mass of an object using a balance?
40. What are the steps for obtaining a desired mass (e.g., 10.00 g) of a substance using a balance?
41. Challenge Question: Calculate the number of molecules of hydrogen there are in 10.0 g H2.
Exercises: Empirical and Molecular Formulas
1. Quantitative analysis of a 5.00-g sample of a gaseous compound yielded the following results: 2.00 g sulfur and 3.00 g oxygen. What is the empirical formula of the compound?
2. What is the molecular formula for butane if it has an empirical formula of C2H5 and each molecule has 10 hydrogen atoms?
3. The percent composition of acetic acid is 39.99% C and 6.73% H. The remainder of the compound is oxygen. The molar mass of acetic acid is 60.06 g/mol. Calculate the molecular formula of acetic acid.
4. What is the empirical formula of a compound that is 29.08% Na, 40.56% S, and 30.36% O?
5. a) Calculate the percent composition of a compound that has 0.90 g of calcium and 1.60 g of chlorine.
b) Determine the empirical formula for this compound.
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