# Tutor profile: Julia L.

## Questions

### Subject: Basic Chemistry

What is the mass of 2.21 moles of phosphorus trichloride?

To answer this question, we must find the mass of phosphorus trichloride. We know that the molecular formula is PCl3, so to find the molecular mass, we need to add the mass of 1 P and 3 Cl. molecular mass = 1 * 30.97 + 3 * 35.45 molecular mass = 137.32 g/mol To find the mass of 2.21 moles of PCl3, we need to multiply the molecular mass by the number of moles given in the problem statement (2.21 moles) mass = 2.21 moles * 137.32 g/mole mass = 303.48 g

### Subject: Calculus

Find the derivative. f(x) = 6x^2 - 9x + 4

To find the derivative, the exponent should be multiplied by the coefficient and the exponent should be subtracted by 1. In the first term, the exponent 2 is multiplied by 6 to get 12 and the exponent 2 is subtracted by 1 to get x. In the second term, the exponent 1 is multiplied by the coefficient 9 to get 9 and the exponent 1 is subtracted by 1 to get 0. In the third term, we need to remember the concept that the derivative of any constant is 0. Therefore, the solution is f'(x) = 12x - 9

### Subject: Algebra

Solve for x. 5x + 3 = 7x – 1

To solve for x in this problem, you need to have all of the terms with x on one side of the equation, and those without on the other side. To do this, subtract 5x from both sides of the equation and –1 from both sides. 3 + 1 = 7x - 5x Then, perform the addition/subtraction 4 = 2x Divide both sides by 2 to solve for x x = 2

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