Recent content by webz

Hmm, then let me try this again. I just want to find the moles of Lactose for now, then I think I got the rest. 1.06 g/mL * 1mol/342g * 12% lactose = 3.719x10^-4 Does that look right? Thanks for the help btw.

Homework Statement Lactose (C12H22O11; MM=342) is a sugar found in mamalian milk. The density of a 12.0% solution is approximately 1.06 g/mL. What is the molarity, molality, and mole fraction of the solution? Homework Equations M=g/L, m=mol/kg, molefraction=mol/mol?? The Attempt...

Oh I get it now! The normal point is at STP. Ugh why didn't I see that before ln(760/65.3)=-25719/8.314(1/x-1/200)=~239K Thank you!

So if the normal boiling point is where the vapor pressure equals the external pressure, I can just set p2/p1 to 1. So I have ln1=-25.179/8.314(1/210-1/T) then T equals the normal boiling point? Eh, I'm confused.

Homework Statement Given the following data, determine the heat of vaporization and normal boiling point of ammonia Temp (K): 200 210 220 230 235 Pressure (respectively)(torr): 65.3 134.3 255.7 456.0 597.0 Homework Equations ln(p2/p1)=-deltaH/R(1/t2-1/t1) The Attempt...

Homework Statement 20g of NH4NO3 (MM=80.05 g/mol) if dissolved in 125g of water in a coffee-cup colorimeter, the temperature falls from 23.5C to 13.4C. Determine 'q' for the dissolving of the compound. Is the process exothermic or endothermic? Homework Equations...

So 0.2g KOH/56.1g/mol KOH = .003 mol and 0.002M HCL * 1.5L HCL = 0.003 mol. So 0.003 mol KOH - 0.003 mol HCl =0, so the pH has to be 7, right? But what if there was still some of a reagent left? Then you would need to calculate the volume of KOH, correct? And how would you do that when you...

It should have been 5.003 x10^-3, not just 5.003. Answer is 46.32mL. Thanks for the help.

Homework Statement Calculate the volume of 0.108 M NaOH solution required to react completely with 145 mL of phosphoric acid solution that is 1.15x10^-2 M. Homework Equations n=MV The Attempt at a Solution NaOH \rightarrow Na^{+}+OH^{-} H_{3}PO_{4} \rightarrow 3H^{+} + PO_{4}^{-}...

Homework Statement Show that 1kg of CaF2 equals 13 mol.Homework Equations Molar mass CaF2 = 78.074g/molThe Attempt at a Solution I can take 78.074g/mol CaF2 * 13 mol = 1014.962 g CaF2 But I can't do this equation backwards, I'm missing a step. I would think if I'm converting g/mol to mol, I...

Thanks for the quick replies! You guys might be seeing me around here, I have to relearn all the calc and chemistry I've ever taken before next semester starts! :P Appreciate your help!

Homework Statement Cross vector A with vector B. A = <0,3,4> B = <4,-4,7> Homework Equations a x b = (a2b3 - a3b2) i + (a3b1 - a1b3) j + (a1b2 - a2b1) k (I think) The Attempt at a Solution AxB= i(21-16)-j(16-0)+k(0-12) = <5,-16,12> I'm unsure if the component 'j' is correct...