Round 5: Find the molar mass of K2Cr2O7 and Fe2(SO4)3.

Round 16: A hydrate of zinc nitrate has the formula Zn(NO3)2*xH2O. If the mass of 1 mol of anhydrous zinc nitrate is 63.37% of the mass of 1 mol of hydrate, what is the value of x?

Round 4: A sample of pure acetic acid CH3COOH contains 1.40 x 10^23 carbon atoms. How many moles of acetic acid are in the sample?

The following reaction proceeds with an 89% yield. C2H5OBr + NaOH --> C2H4O + NaBr + H2O What mass of C2H4O can be obtained when 3.61 x 10^23 molecules of C2H5OBr react with excess sodium hydroxide?

Round 7: Sodium chloride (NaCl) can be used to melt snow. How many moles of sodium chloride are in a 10kg bag?

Round 15: Tartaric acid, also known as Cream of Tartar, is used in baking. Its empirical formula is C2H3O3. If 1.00mol of tartaric acid contains 3.61x1024 oxygen atoms, what is the molecular formula of tartaric acid?

Round 2: Rubidium ignites spontaneously when exposed to oxygen to form Rb2O. Rubidium exists as two isotopes: Rb-85 (84.91u) and Rb-87 (86.91u). If the average atomic mass of Rubidium is 85.47u, determine the percentage abundance of Rb-85.

Round 13: Compound X contains 69.9% carbon, 6.86% hydrogen, and 23.3% oxygen. Determine the empirical formula of Compound X.

Round 3: A small pin contains 0.0178 mol of iron (Fe). How many atoms of iron are in the pin?

Round 6: Which sample has the largest mass? A) 5.00 mol of C B) 1.50 mol of Cl2 C) 0.50 mol of C6H12O6

Round 11: Indigo (C16H10N2O2) is the common name of the dye that gives blue jeans their characteristic colour. Calculate the mass of oxygen in 25.0 g of indigo.

Dinitrogen pentoxide is a white solid. When heated it decomposes to produce nitrogen dioxide and oxygen. 2N2O5(s) --> 4NO2(g) + O2(g) How many grams of oxygen gas will be produced in this reaction when 2.34g of NO2 are made?