# Tutor profile: Anthony H.

## Questions

### Subject: Chemistry

How do I determine the geometric shape of the following compounds? NH3 H20

Starting out with the first compound the NH3: Since each of the hydrogens only have one electron and need two total, each hydrogen can only form 1 bond. Given this each hydrogen must make one bond with the nitrogen. However the nitrogen has 5 valence electrons so there are 2 electrons left unpaired, and these act to cause some interactions between the unpaired electrons and the bonds of N-H, this causes the shape to trigonal pyramid. With respect to the H20 now: The hydrogens will behave the same way we talked about earlier wanting only one bond each. However the oxygen has one more valence electron than nitrogen did for a total of 6 valence electrons. Given that there are 6 valence electrons this means that you have 4 unpaired electrons once the hydrogens bond with the oxygen. These four unpaired electrons cause repulsion between the bonds and the other unpaired electrons which causes a bent shape, ironically the geometric shape of this compound is "bent." Good job!

### Subject: Basic Chemistry

Determine whether these two compounds are soluble in water: NaCl HgSO4

In order to evaluate this question we must first address the criteria for a compound to be soluble, in this case, we will start with the NaCl. If you go online and find a solubility chart you will discover that Cl is soluble in most salts (for example Na) with the exception of Ag+, Pb+ and Hg2+, therefore we can determine that NaCl is soluble in water. Now with respect to the HgSO4, SO4(2-) is soluble in everything except when attached to Ba2+, Pb2+, Ca2+ and Sr2+. Therefore we understand that HgSO4 is not soluble in water! Good job!

### Subject: Algebra

How would I evaluate the expression below, step by step? For, f(f(x)) for f(x)= 24/(x+1) when x=2

The first step is to solve the inside of the expression f(f(x)) so we must first evaluate f(x), which is below: f(2)=24/(2+1)=8 since this expression yielded us an 8 we will now use that to evaluate the other f(x) expression, shown below: f(8)=24/(8+1)= 2.67 So to recap, we first evaluated the inner f(2)=8 then took that 8 and evaluated the outer f(x) to be f(8)=2.67 Good job!

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