# Electric Force problem involving HCl and Br- on coordinate axis

1. Jan 11, 2014

### bbuilder

1. The problem statement, all variables and given/known data

A hydrogen chloride molecule (HCl) has a partial positive charge on the hydrogen atom and a partial negative charge on the chlorine atom. The HCl molecule is placed at

A.
There will be force on the bromide ion in the +x direction.

B.
There will be force on the bromide ion in the -x​ direction.

C.
There will be force on the bromide ion in the +y​
There will be no force on the bromide ion. The attractive force from the positively charged hydrogen will be cancelled out by the repulsive force of the negatively charged chlorine.

2. Relevant equations
p=qd

3. The attempt at a solution
I might be overthinking this problem. I was thinking that the bromide ion be in the positive x-direction to attract it to the partial positive negative ion. I'm confused about how the y-direction might come into play in this problem. I was also thinking that these charges might cancel out because they are directly opposite of each other on the x-axis.

Last edited: Jan 11, 2014
2. Jan 11, 2014

### ehild

Hi bbuilder, welcome to PF.

Make a drawing showing the position of the atoms, and draw arrows showing the magnitude and direction of the forces.

ehild

3. Jan 11, 2014

### bbuilder

The negatively charged chloride is on the -x-axis. The positively charged hydrogen is on the chloride ion has a force on the bromide ion at a positive angle above the horizontal. The positively

Last edited: Jan 11, 2014
4. Jan 11, 2014

### ehild

See the picture. As the HCl molecule is neutral, the positive charge on the hydrogen is equal in magnitude to that of the negative charge on the chlorine. As they are at equal distances from the bromine atom, both the hydrogen and the chlorine atom exert equal forces on the bromine, but the force of the hydrogen is attractive, that of the chlorine is repulsive. See the picture.

What is the direction of the resultant force on the bromine?

Read the problem carefully. All questions refer to the force applied on the bromine atom.

ehild.

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