<p>I have two hard questions, please help me:</p>
<p>1) at 19.0 degree C a liquid has a 40mmHg vapor pressure; its normal boiling oint is 78.3. what is its enthalpy of vaporization in kJ(mol)^-1</p>
<p>the answer is 42 kJ(mol)^-1
no idea how to get it, please show me the steps</p>
<p>2) what are the products of the following reactions HNO3 (aq) + Cu (s) --> ?</p>
<p>2) Is probably Copper Nitrate and H30+....not sure though.</p>
<p>2) nothing will happen since Cu is less chemically reactive that H.
there is a table for this reactivity stuff, about which elements can replace H in a reaction...
although I am not quite sure about this I think it looked like this
K>Ca>Na>Mg>Al>Zn>Fe>Sn>Pb> H >Cu>Ag>Hg>Au but you should check about this order, cause it has been a while since i last reviewed it.</p>
<p>thanks, i have another question: which one has the largest intermolecular force CH3Cl, CH2Cl2, or CHCl3? please explain, thanks!</p>
<p>CHCL3 does i think,
the Cl is more attracted to other Cls than C-H is...... my guess is CHCl3</p>
<p>CHCl3 for sure...since Cl is more electronegative and thus attracts electrons from the central C atom....and thus develops an attractive force...</p>
<p>1) Use the equation ln(pressure1 / pressure2) = (enthalpy of vap / R ) (1 / temp2 - 1 / temp1). I forget what the name of the equation is, but its probably somewhere in your chem book. </p>
<p>R is a constant, so plug in what you already know and solve for enthalpy of vap.</p>
<p>ln(40mmHg / 760 mmHg) = (enthalpy of vap / 0.0083145 kj per mol)( 1 / 351.3K - 1 / 292k)</p>
<p>-2.944 = (enthalpy of vap / 0.0083145 kj per mol)( -0.000578)</p>
<p>5180 = enthalpy of vap / 0.0083145 </p>
<p>enthalpy of vap = 43 </p>
<p>My sig figs are screwed up, so the answer came out one digit too high, but if you keep all the numbers on the screen of your calculator, it should come out to be 42.3. Also, sorry about forgetting to put in the units half the time. Hope that helps.</p>
<p>For the 2nd question:
3Cu + 8HNO3=3Cu(NO3)2 + 2NO + H2O</p>