# Tutor profile: Harriet Jane C.

## Questions

### Subject: Chemistry

How can I determine the polarity of a molecule?

A molecule is polar if there is net dipole moment (or net pull of electrons) on the molecule. The best way to determine the polarity is to draw first the lewis structure of the compound with consideration of the 3D geometry. Once drawn, we assign the pull of the electrons which is towards the more electronegative atom. Imagine then the electronegative atoms pull at the same time. If there is an unbalance in the molecule, it will have a net dipole moment and it will be polar. Otherwise, if the pull of the electrons cancel each other, then it is non-polar.

### Subject: Calculus

How can I solve the function: dy/dx = 2x?

The equation is a differential equation. It is different from the other equations in the sense that this equation needs to be solved to determine the function involved. It will also determine the relationship of variables (in this case, x and y) To solve this problem, we arrange the equation such that the same variable is on one side: dy = 2x dx Next is we integrate it where we remove the d_ variables. The integral of dy is y while for 2x, it is x^2 followed by a constant So this is y = x^2 + k

### Subject: Basic Chemistry

In a liquid chromatography, how can I know which will elute first?

The elution will depend on the stationary and mobile phase used. If you are using a non-polar stationary phase and your mobile phase is more polar than the stationary phase, the sample that will elute first is the compound which is more polar. the compound which is least polar will stay more on the column and will take more time before it elutes and reach the detector.

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