# Recent content by fghtffyrdmns

1. ### Integral optimization

Homework Statement A circular disk of radius r is used in an evaporator and is rotated in a vertical plane. If it is to be partially submerged in the liquids as to maximize the exposed wetted area of the disk, show that the center of the disk should be positioned at a height r/ \sqrt{1+\pi^2}...
2. ### What volume of this solution is required to make 1.25 L

v1 = c2v2/c1 v1 = (1.25 L)(2.75 mol/L)/(15.8585 mol/L) = 0.217 L.
3. ### Neutralization reaction

If you multiply the H3PO4 by 3, you would have a ratio of 1:1 with NaOH:H3PO4. So you could write c1v1=3c2v2?
4. ### Inverse trig functions

ahhh so could I write sinA = \theta?
5. ### Inverse trig functions

Homework Statement Determine sin(arctan(3)) The Attempt at a Solution I do not know how to start this. No special triangles : (.
6. ### Trig ratios

sin(pi)= 0 cos (pi) = -1 tan (pi) =0. Is that all?
7. ### Trig ratios

Homework Statement Find the trigonometric ratios sin\theta, cos\theta, tan\theta for the angle \theta = 14\pi. If a ratio does not exist or is undefined, write "DNE". The Attempt at a Solution I know that the other equivalent angle for 15pi is just pi. But I do not know how to write the...
8. ### What volume of this solution is required to make 1.25 L

(0.85)(1.83 g/mL)(1000 mL/L)(1 mol/98.086 g) This gives you the concentration Then you can simply find the volume with c1v1=c2v2.
9. ### Neutralization reaction

The H3PO4. This way you would have a 1:1 ration, correct?
10. ### Neutralization reaction

Yes, I learnt the hard way. I wrote the balanced equation of H3PO4 + 3 NaOH -> 3 H2O + Na3PO4 3CnaohVnaoh = Ch3po4Vh3po4 Is this wrong?
11. ### What volume of this solution is required to make 1.25 L

That's what's confusing me. If I do this, I get the wrong answer.
12. ### What volume of this solution is required to make 1.25 L

Homework Statement An aqueous stock solution is 85.0% H2SO4 by mass and its density is 1.83 g/mL. What volume of this solution is required to make 1.25 L of 2.75 mol/L H2SO4(aq)? Give your answer in millilitres, accurate to three significant figures. Homework Equations c1v1=c2v2 The...
13. ### Neutralization reaction

But I'm trying to find the volume of NaOH. There's 3:1 ratio.
14. ### Neutralization reaction

so, 3c1v1 = c2v2 then v1 = c2v2/3c1 ? This would give me 6.80x10^-2 L.

Elaborate.