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 1: Naturally occurring silver exists as two isotopes. From the table above, calculate the average atomic mass of silver.

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

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

Round 14: Olive oil is used widely in cooking. Oleic acid, a component of olive oil, contains 76.54% carbon, 12.13% hydrogen and 11.33% oxygen by mass. What is the empirical formula of oleic acid?

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?

2NaN3(s) --> 3N2(g) + 2Na(s) To inflate the air bag on the driver’s side of the car, 80.0g of N2 is required. What mass of NaN3 is needed to produce 80.0g of N2?

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?

Round 12: A compound consists of 17.6% hydrogen and 82.4% nitrogen. Determine the empirical formula of the compound.

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

Round 10: Calculate the mass percent of nitrogen in Sr(NO3)2.

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