How many grams of naoh were dissolved to make a 1.25 l solution of 2.92 m naoh?

Explanation:

1) Data:

a) mass of solute = ?

b) volume of solution = 1.25 liter

c) M = 2.92 mol/liter

d) solute NaOH

2) Formulae:

a) Molarity, M = number of moles of solute / volume of solution in liters

b) mass in grams = molar mass × number of moles

3) Solution:

a) Calculate number of moles of solute:

        ⇒ number of moles of solute = M × volume of solution in liters

        ⇒ number of moles of solute = 2.92 mol/liter × 1.25 liter = 3.65 mol

b) Molar mass of NaOH = 39.997 g/mol (you can take this number from internet or calculate it using the atomic masses of Na, O, and H).

c) Calculate the mass of solute:

The answer must be reported with 3 significant figures, so it is 146. g.

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.