Electric net charge problem

[dmolson]

Suppose a 1.68 g nugget of pure gold has zero net charge. What would be its net charge after it has 1% of its electrons removed?

Answer in C
Mass
Electric charge of proton = 1.602e-19 C 1.673e-27 kg
Electric charge of electron = -1.602e-19 C 9.109e-31 kg
Electron charge of neutron = 0 1.675e-27 kg

I have attempted one answer of 1.602e-21 C, but I am really confused at how to obtain the solution. I know this is supposed to be an easy problem, but I am just confused. Any assistance would be greatly appreciated.

 

[turdferguson]

How many electrons are in 1.68 grams?

 

[chemhelper]

The first thing that is needed is to convert 1.68 g gold into moles, which comes out to 1.68 / 196.97 = 0.0085 mol gold.

Since it starts off as a neutral sample, there must be exactly one electron for every proton present. Every gold atom has 79 protons, which means each atom would have initially 79 electrons.

So, convert the moles of gold into atoms by (0.0085 mol)*(6.022*10^23 atoms/mol) = 5.14 x 10^21 atoms of gold. This implies that there are (5.14 x 10^21)*(79 protons/atom)*(1 electron/1 proton) = 4.058 x 10^23 electrons present. One percent of these gone corresponds to (1-0.01)*(4.058 x 10^23) = 4.02 x 10^23 electrons.

Now, find the charge on the protons and electrons
4.023 x 10^23 electrons*(-1.602e-19 C) = -64453 C
4.064 x 10^23 protons*(1.602e-19 C) = 65104 C

Add the charges together to get +651 C

Concept check: This makes sense because if the sample is losing electrons, the net charge of the sample should increase

 

[cristo]

The first thing that is needed is to convert 1.68 g gold into moles, which comes out to 1.68 / 196.97 = 0.0085 mol gold.

Since it starts off as a neutral sample, there must be exactly one electron for every proton present. Every gold atom has 79 protons, which means each atom would have initially 79 electrons.

So, convert the moles of gold into atoms by (0.0085 mol)*(6.022*10^23 atoms/mol) = 5.14 x 10^21 atoms of gold. This implies that there are (5.14 x 10^21)*(79 protons/atom)*(1 electron/1 proton) = 4.058 x 10^23 electrons present. One percent of these gone corresponds to (1-0.01)*(4.058 x 10^23) = 4.02 x 10^23 electrons.

Now, find the charge on the protons and electrons
4.023 x 10^23 electrons*(-1.602e-19 C) = -64453 C
4.064 x 10^23 protons*(1.602e-19 C) = 65104 C

Add the charges together to get +651 C

Concept check: This makes sense because if the sample is losing electrons, the net charge of the sample should increase
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