# CHE 117 Practice Problems for Final

## Lewis dot structures

Draw the Lewis dot structure for each of the following compounds. Predict the compounds shape. Determine whether the compound will be polar or nonpolar

NH4+      tetrahedral, nonpolar

CH2O      trigonal planar, polar

AlCl3      trigonal planar, nonpolar

## Electron configurations

Write the electron configuration for each of the following elements.

N,       1s22s22p3

Cl,       1s22s22p63s23p5

Zn,       1s22s22p63s23p64s23d10

## More pH problems

Determine the pH or [H+] for each of the following solutions.

[HCl] = 2.35 x 10-4,       3.629

[HNO3] = 0.000452,       2.344

[KOH] = 4.65 x 10-4,       10.667

sodium carbonate with [-OH] = 5.6 x 10-5,       9.748

potassium acetate with pH = 10.52,       3.02 x 10-11

benzoic acid with pH = 5.36,       4.36 x 10-6

## More limiting reagent problems

Consider the following reaction. If you have 56.43 grams of carbon monoxide (CO) and 35.73 grams of hydrogen (H2), how many grams of methanol can form?

CO      +      2 H2 CH3OH
64.49 grams of CH3OH can form. CO is the limiting reagent.

Consider the following reaction. If you have 46.5 grams of zinc oxide (ZnO) and 36.5 grams of coke (C), how much zinc (Zn) can you form?

ZnO      +      C Zn      +      CO
37.4 grams of Zn can form. ZnO is the limiting reagent.

Consider the following reaction. If you have 35.4 grams of bromine (Br2) and 76.3 grams of aluminum (Al), how much aluminum bromide (AlBr3) can you form?

2 Al      +      3 Br2 2 AlBr3
39.39 grams of AlBr3. Br2 is the limiting reagent.