REVIEW : MOLE

1. You have 7.57 g of each of the following elements: Si, S, Se, Sr, and Sn. Which sample contains the largest number of atoms? Si S Se Sr Sn Si

2. If 1. 00 g of an unknown molecular compound contains 8 2. If 1.00 g of an unknown molecular compound contains 8.35 x 1021 molecules, what is its molar mass? a) 44.0 g/mol b) 66.4 g/mol c) 72.1 g/mol d) 98.1 g/mol e) 132 g/mol 72.1 g/mol

3. If 5.15 g Fe(NO3)3 is dissolved in enough water to make exactly 150.0 mL of solution, what is the molar concentration of nitrate ion? Molar mass is 241.85 g/mol 0.00319 M b) 0.0343 M c) 0.142 M d) 0.313 M e) 0.426 M 0.426 M

4.0 x10-2 x 1 mol CalCl2 x 1 Liter = 8.0 x 10-2 L What volume of 0.25 M calcium chloride solution would contain 4.0 x 10-2 mol of chloride ions? 4.0 x10-2 x 1 mol CalCl2 x 1 Liter = 8.0 x 10-2 L 2 mol of Cl- .25 mol

4. If 25.00 mL of 4.50 M NaOH(aq) is diluted with water to a volume of 750.0 mL, what is the molarity of the diluted NaOH(aq)? 0.0333 M 0.150 M 0.155 M 6.67 M 1.35 x 103 M 0.150 M

5. Tin metal and purple iodine combine to form orange, solid tin iodide with an unknown formula, SnxIy. Sn (s) + I2(s) --> SnxIy Weighed quantities of Sn and I2 are combined, where the quantity of Sn is more than is needed to react with all of the iodine. After SnxIy has been formed, it is isolated by filtration. The mass of excess tin is also determined. The following data was collected: Mass of Sn in original mixture = 1.056 g Mass of I2 in original mixture = 1.947 g Mass of tin in remaining = 0.601 g What is the formula of SnxIy? SnI4

A student reacted 0.273 grams of magnesium metal with atomic gaseous nitrogen, producing a residue having a mass of 0.378 grams. What is the empirical formula of the ionic compound? 0.378 g - 0.273 g = 0.105 g = mass of nitrogen   0.105 g / 14.01 g/mol = 0.007495 mol N 0.273 g / 24.3 g/mol = 0.0112 mol Mg 0.0112 / 0.007495 = 1.50 : 1 = 3 : 2 => Mg3N2

You want to know the value of x in blue, hydrated copper (II) sulfate, CuSO4*XH2O. In the lab, you weigh out 1.023 g of the solid. After heating the solid thoroughly in a porclein crucible, 0.654 g of nearly white, anhydrous copper (II) sulfate remains. What is the formula and the name of the hydrate? CuSO4x5H2O

6. What is the percent of chlorine in (Z) 1,2- dichloro-3-hexene? Draw the molecule before performing the calculation. 70.90 g/mol Cl _____________ x100 = 46.32% 153.06g/mol