# Tutor profile: Sean T.

## Questions

### Subject: Material Science

What is the primary alloying element of steel alloys? What type of lattice position does this element have? Why is carbon such an essential element in steel alloys?

The primary element in steel alloys is carbon, this element is small enough to fit in between iron molecules and thus fits in a interstitial atomic positions. Carbon is the primary element driver for strength in steel alloys. It controls the phase transformation and hardenability of steel alloys.

### Subject: Chemistry

Determine the mass percentage of carbon in the following formula: CH3

We would first find the total mass of the molecule by referencing the atomic weights(AW) found in the periodic table. Carbon has a AW of 12, and hydrogen has a approximate atomic weight of 1. Since there are 3 hydrogen molecules we would multiply the hydrogen content by 3. By adding the carbon and the three hydrogen atoms we come up with a molecular mass of 12+3=15. Since we want to know the mass percentage of carbon we divide the mass of the carbon by the total mass of the molecule (12/15). This yields a mass percentage of 0.8 or 80%. If we wanted to then know the hydrogen content we would just subtract the 80% from 100% yielding a hydrogen mass percentage of 20%.

### Subject: Algebra

Solve the system of equations: 2x+y=5 10x-y=7

We would add the system of equations since there is one variable that has opposite signs that allow an easy cancellation. The additive solution would be 12x=12. This would yield an answer of x=1. We would then plug the x value back into the equation to solve for y. This would equal 2(1)+y=5 making y=3. We can check the work by plugging both variable into the formulas to see if the values match 2(1)+3=5 and 10(1)-3=7.

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