1. What is the empirical formula of a compound composed of 3.25% hydrogen (H), 19.36% carbon (C), and 77.39% oxygen (O) by mass? 2. A compound with the empirical formula CH2 has a molar mass of 84 g/mol. What is the molecular formula for this compound? 3. A 15.85 g sample of Mo2O3(s) is converted completely to another molybdenum oxide by adding oxygen. The new oxide has a mass of 16.91 g. Add subscripts below to correctly identify the empirical formula of the new oxide. 4. A 7.99 g sample of a compound contains 2.55 g potassium (K), 2.31 g chlorine (Cl), and oxygen (O). Calculate the empirical formula. 5. A compound is 54.53% C, 9.15% H, and 36.32% O by mass. What is its empirical formula? 6. The molecular mass of the compound is 132 amu. What is the molecular formula? 7. How many grams of a 14.0% sugar solution contain 38.5 g of sugar? 8. You need to dissolve CaCl2 in water to make a mixture that is 33.0% calcium chloride by mass. If the total mass of the mixture is 741.4 g, what masses of CaCl2 and water should be used? ( Mass of CaCl2) ( Mass of H20) 9. A solution contains 4.40 g of solute in 11.6 g of solvent. What is the mass percent of the solute in the solution? 10. A 4.68 g sample of a laboratory solution contains 1.32 g of acid. What is the concentration of the solution as a mass percentage? 11. How many moles of NaOH are present in 19.0 mL of 0.280 M NaOH? 12. Calculate the number of moles of solute in 93.83 mL of 0.1595 M K2Cr2O7(aq). 13. The mass percentage of hydrochloric acid within a solution is 40.00%. Given that the density of this solution is 1.200 g/mL, find the molarity of the solution. 14. How many grams of solute are present in 835 mL of 0.710 M KBr? 15. calculate the molarity a) 21.7 g of NaCl in 799 mL of solution. = in (M) b) 0.500 mol of NaOH in 1.40 L of solution.= in (M) 16. Calculate the molarity a) 0.250 mol of Na2S in 1.80 L of solution. b) 34.7 g of MgS in 911 mL of solution. 17.How many milliliters of 12.0 M HCl(aq) are needed to prepare 915.0 mL of 1.00 M HCl(aq)? 18. What is the concentration of a solution made by diluting 35 mL of 6.0 M HCl to a final volume of 750 mL?