Question

1). Determine the thickness of a piece of platinum foil that has a mass of 2.000 g, and has length and width of 9.85 cm and 5.20 cm, respectively. Note that the density of platinum is 21.45 g/cm3 .

2). A 100.06-g piece of tungsten metal is dropped into a graduated cylinder containing water. If the water level in the graduated cylinder is observed to increase from 14.5 mL to 19.7 mL, what is the density of tungsten?

3.) What is the mass of a sheet of lead which measures 36.2 mm x 25.8 mm x 193.1 mm, if the density of lead is 11.35 g/cm3 ?

4.) An unknown solution was found to produce a bright yellow-orange flame color when exposed to a Bunsen burner flame. Which element was present in the unknown solution? lithium sodium potassium barium strontium

5). Sketch the Lewis structure and predict the molecular shape(s) for NH2OH, HONO, and HOCN.

7. An alum hydrate was analyzed by decomposition. The following data was collected: mass of beaker and watchglass 92.18 g mass of beaker, watchglass, and alum hydrate 93.11 g mass of beaker, watchglass, and anhydrate 92.69 g Calculate the experimental percentage of water.

8. The analysis of an unknown hydrate yielded an experimental percentage of water equal to 45.5%. If the molar mass of the anhydrous compound (NiCl2) is 129.59 g/mol, what is the formula of the hydrate (NiCl2  xH2O)?

9. What is the empirical formula of a compound which has the molecular formula C4H6O2?

10. A 1.349-g piece of aluminum is allowed to react with excess sulfur, yielding 3.754 g of aluminum sulfide. Determine the empirical formula of aluminum sulfide. 11. The empirical formula of phosphorus oxide is determined to be P2O5. What is the molecular formula of phosphorus oxide if the molecular mass if 285 amu?

12. Balance the following chemical equations: ___Mg(s) + ___O2(g) + heat  ___MgO(s) ___Na2CO3(s) + heat  ___Na2O(s) + ___CO2(g)

13. A test tube contains 1.47 g of sodium hydrogen carbonate was heated, producing 0.89 g of sodium carbonate. What is the percent yield of sodium carbonate?

14. A 1.55-g unknown sample containing lithium hydrogen carbonate is decomposed with heat. If the mass is observed to decrease by 0.23 g, what is the percentage of lithium hydrogen carbonate in the unknown mixture? (The actual products are H2O and CO2) LiHCO3(s) + heat  Li2CO3(s) + H2CO3(g)

15. Sodium metal reacts with water to produce sodium hydroxide and hydrogen gas. If 356 mL of hydrogen gas are collect at STP, then how much sodium reacted?

16. What is the density of a gas at STP, if the molar mass of the gas is equal to 20.18 g/mol?

17. A 10.0-mL sample of a sodium chloride solution was heated to dryness. From the following data, calculate the mass-mass percent of the sodium chloride solution (prior to heating): mass of evaporation dish 46.28 g mass of evaporation dish and solution 57.19 g mass of evaporation dish and sodium chloride 47.36 g

18. What is the molar concentration of the solution in the previous problem?

19. A 10.0-mL sample of acetic acid is titrated with sodium hydroxide solution. If 35.89 mL of 0.2531 M sodium hydroxide is required to reach the end point, what is the molar concentration of the acetic acid?

20. A 30.0-0 mL sample of 6.0 M hydrochloric acid was mixed with 50.0 mL of water. What is the new concentration of the hydrochloric acid?

21. Write the following chemical equations as balanced net-ionic equations: Al(NO3)3(aq) + (NH4)2CO3(aq)  Al2(CO3)3(s) + NH4NO3(aq) H3PO4(aq) + Ba(OH)2(aq)  Ba3(PO4)2(s) + H2O(l)

22. State whether or not aqueous solutions of the following substances will be highly or slightly ionized: NH4OH Al(OH)3 H2SO4 LiOH Na3PO4 BaCl2 HC2H3O2

Answer 1

Density - mays Volume Volume nen Densih thicknes 1 (length & width x mars densily thickness & (9.8 5x 5.200 cm2 a 21.45g/m3 0.09324 thicknes: 51.22 10-3 1.82 x