// JavaScript Document
//11/18/02-updated netscape 7
thepage="85 - Combustion Analysis"
//globals
cell="<input class='text' type=text size=5 value=''>"
thebutton="<br><input type=button onClick='answer(this.form)' value='Check Answer'></form>"
var ie4 = (document.all) ? true : false;
corrt=0
attempts=0
tried=0
totl=0
elems=0
xx=0
themass=0
percents=0
formula=""
gfw=0
catsub=""
ansub=""
thequest=thesolution=""
theanswer=closephrase=""
qphrase=new Array()
qphrase[0]=new Array("A sample of a compound containing "," is subjected to combustion analysis to determine the quantities of C and H present.")
nextphrase=new Array(" Using a second sample, the "," is analyzed by converting it to"," The results of the analysis are shown below.")
lastcmpd=new Array("","CO<sub>2</sub>","H<sub>2</sub>O"," NO<SUB>2</SUB>",""," Ca<SUB>3</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB>","BaSO<SUB>4</SUB>"," AgCl"," AgBr"," CuI")
factors=new Array(1,1,1,.304,1,.1997,.137,.247,.425,.666)
ansphrase="The solution to this problem involves working backward from the data for each analysis toward the initial compound. The solution will present each step in this process. Note that though it is true that for compounds with only three elements, the third value can be obtained by difference, the presentation here will determine such values from the analytical data, when possible. For the analysis of C and H, the masses of CO<SUB>2</SUB> and H<SUB>2</SUB>0 are first converted into the masses of C and H, respectively, and then to percents:<br>"
conclude=new Array("The next element is determined similarly, using the second sample.<br>","The final element is obtained by difference.<br>")
function repelement(name,sym,an,mass){
	this.name=name
	this.sym=sym
	this.an=an
	this.mass=mass
	}
reps=new Array()
reps[0]=""
reps[1]=new repelement("hydrogen","H",1,1.0079)
reps[2]=new repelement("carbon","C",6,12.011)
reps[3]=new repelement("nitrogen","N",7,14.0067)
reps[4]=new repelement("oxygen","O",8,15.9994)
reps[5]=new repelement("phosphorous","P",15,30.97376)
reps[6]=new repelement("sulfur","S",16,32.066,32)
reps[7]=new repelement("chlorine","Cl",17,35.453)
reps[8]=new repelement("bromine","Br",35,79.904)
reps[9]=new repelement("iodine","I",53,126.9045)
atoms=new Array(" C"," H"," N"," O"," P"," S"," Cl"," Br"," I")
multipliers=new Array("12/44","2/18","14/46",1,"61.94/310.2","32.06/233.6","35.45/143.35","79.91/187.8","126.9/190.4")
equations=""
solved=new Array()
function buildeqns(){
	equations=new Array()
	for(var j=0;j<atoms.length;j++)equations[j]="Mass of"+atoms[j]+"=Mass of "+lastcmpd[j+1]+" &#215; "+multipliers[j];
	equations[3]="Oxygen is obtained by difference:"
}
		
function clear(){
	clearansspot()
	document.forms[0].results.value=""
	attempts=0
	tried=0
}
function startit(){
	buildeqns()
	tried=0
	totl++
	document.forms[0].total.value=totl
	clear()
	buildcmpd()
}
function buildcmpd(){
	elems=new Array()
	themass=new Array()
	percents=new Array()
	c=2+Math.floor(10*Math.random())
	h=2*c+2
	h=h-removeh(h/2)
	elems[0]=new Array(reps[2].sym,reps[2].mass,c,1)
	elems[1]=new Array(reps[1].sym,reps[1].mass,h,2)
	option=Math.ceil(7*Math.random())
	if(option==1){
		elems[elems.length]=new Array(reps[5].sym,reps[5].mass,1,5)
		h++
		}
	if(option==2 || option==3){
		n=Math.ceil(2*Math.random())
		elems[elems.length]=new Array(reps[3].sym,reps[3].mass,n,3)
		h++
		}
	if(option==2 || option==4 ||option==6){
		o=Math.ceil(2*Math.random())
		elems[elems.length]=new Array(reps[4].sym,reps[4].mass,o,4)
		}
	if(option==2 || option==5){
		s=Math.ceil(2*Math.random())
		elems[elems.length]=new Array(reps[6].sym,reps[6].mass,s,6)
		}
	if(option>4){
		hal=Math.ceil(2*Math.random())
		whichhal=7+Math.floor(3*Math.random())
		elems[elems.length]=new Array(reps[whichhal].sym,reps[whichhal].mass,hal,whichhal)
		h--
		}
	if(elems.length>4){totl--;buildcmpd()}
	else{
	formula="";
	gfw=0
	for(j=0;j<elems.length;j++){
		themass[j]=(elems[j][1]*elems[j][2])
		formula=formula+elems[j][0];
		gfw+=themass[j]
		if(elems[j][2]>1)formula=formula+("<sub>"+elems[j][2]+"</sub>")
		}
	gfw=number(gfw,4,3)
	for(var j=0;j<themass.length;j++)percents[j]=number(100*themass[j]/gfw,3,3);
	burnit()
	}
}	
function removeh(x){
	drop=Math.floor(Math.random()*x)
	if(drop%2!=0)drop+=1
	return drop
}
function getsubs(x,y){
if(x>y){
	if(x%y==0){
		catsub=1
		ansub=Math.ceil(x/y)}
	else{
	 	catsub=y
		ansub=x
	    }
	}
if(y>x){
	if(y%x==0){
		catsub=Math.ceil(y/x)
		ansub=1}
	else{
	 	catsub=y
		ansub=x
	    }
	}
}
function burnit(){
	sample=new Array()
	sample[0]=0
	while(sample[0]<2)sample[0]=number(5*Math.random(),4,3)
	comass=number((percents[0]*sample[0]/100*3.667),4,3)
	hmass=number((percents[1]*sample[0]/100*9),4,3)
	line1="<br><b>Sample 1 Mass:</b>"+sample[0]+"g &#8594; <b>CO<SUB>2</SUB> Mass: </b>"+comass+"g; <b>H<SUB>2</SUB>O Mass: </b>"+hmass+"g"
	masses=new Array(comass,hmass)
	sample[1]=0
	while(sample[1]<2)sample[1]=number(5*Math.random(),4,3)
	lastmass=""
	closephrase=""
	exmass=0
	if(elems.length==3){
		if(elems[2][3]!=4){closephrase=nextphrase[0]+elems[2][0]+nextphrase[1]+lastcmpd[elems[2][3]];
		exmass=number((percents[2]*sample[1]/(100*factors[elems[2][3]])),4,3)
		xx=elems[2][3]
		}}
	if(elems.length==4){
		if(elems[2][3]==4){
			closephrase=nextphrase[0]+elems[3][0]+nextphrase[1]+lastcmpd[elems[3][3]]
			exmass=number((percents[3]*sample[1]/(100*factors[elems[3][3]])),4,3)
			xx=elems[3][3]
			}
		else{
			closephrase=nextphrase[0]+elems[2][0]+nextphrase[1]+lastcmpd[elems[2][3]]
			exmass=number((percents[2]*sample[1]/(100*factors[elems[2][3]])),4,3)
			xx=elems[2][3]
			}
		}
	line2=""
	if(exmass>0){
		line2="<br><b>Sample 2 Mass:</b>"+sample[1]+"g &#8594; <b>"+lastcmpd[xx]+": </b>"+exmass+"g"
		masses[masses.length]=exmass
		}
	closephrase+=nextphrase[2]+line1+line2
	buildquest()
	buildanswer(sample,masses)
}	
function buildquest(){
	inserts=elems[0][0]
	for(var j=1;j<elems.length;j++){
		j<(elems.length-1)?inserts+=","+elems[j][0]:inserts+=" and "+elems[j][0];
	}
	thequest=qphrase[0][0]+inserts+qphrase[0][1]+closephrase
	buildquestion()
}
function buildanswer(sample,masses){
	themass=new Array()
	percents=new Array()
	themass[0]=number(masses[0]*12/44,4,3)
	themass[1]=number(masses[1]/9,4,3)
	percents[0]=number(themass[0]/sample[0]*100,4,3)
	percents[1]=number(themass[1]/sample[0]*100,4,3)
	if(masses.length==3){
		themass[2]=number(masses[2]*factors[xx],4,3)
		tpercent=number(themass[2]/sample[1]*100,4,3)
	}	
	if(elems.length==3){
		if(masses.length==2)percents[2]=number(100-(1*percents[0]+1*percents[1]),4,3);
		else percents[2]=tpercent;
		}
	if(elems.length==4){
		if(elems[2][3]==4){percents[3]=tpercent;percents[2]=number(100-(1*percents[0]+1*percents[1]+1*percents[3]),4,3)}
		else {percents[2]=tpercent;percents[3]=number(100-(1*percents[0]+1*percents[1]+1*percents[2]),4,3)} 
	}
	getsolved(masses,themass,percents)
	theanswer=ansphrase
	for(var j=0;j<2;j++)if(j<2)theanswer+=equations[elems[j][3]-1]+"<br>"+solved[j]+"<br>";
	for(var j=2;j<elems.length;j++){
		if(j==2){
		elems[2][3]==4?theanswer+=equations[3]+"<br>"+solved[2]+"<br>":theanswer+=conclude[0]+equations[elems[j][3]-1]+"<br>"+solved[j]+"<br>";
		}
		if(j==3){
		if(elems[2][3]==4)theanswer+=conclude[0]+equations[elems[j][3]-1]+"<br>"+solved[3];
		else{
		elems[3][3]==4?theanswer+=equations[3]+"<br>"+solved[3]+"<br>":theanswer+=conclude[1]+"%"+elems[3][0]+"="+solved[j]+"<br>";
		}}
	} 
}
function getsolved(masses,themass,percents){
	solved=new Array()
	solved[0]=masses[0]+" &#215; "+multipliers[0]+"="+themass[0]+"<br>%"+atoms[0]+" = "+themass[0]+" &#247; "+sample[0]+" &#215; 100=<b>"+percents[0]+"%</b>"
	solved[1]=masses[1]+" &#215; "+multipliers[1]+"="+themass[1]+"<br>%"+atoms[1]+" = "+themass[1]+" &#247; "+sample[0]+" &#215; 100=<b>"+percents[1]+"%</b>"
	if(elems.length==3){
		if(masses.length==2)solved[2]=100+" - ("+percents[0]+"+"+percents[1]+") = <b>"+percents[2]+"%</b>"
		else solved[2]=masses[2]+" &#215; "+multipliers[xx-1]+" = "+themass[2]+"<br>%"+atoms[xx-1]+" = "+themass[2]+" &#247; "+sample[1]+" &#215; 100=<b>"+percents[2]+"%</b>"
		}
	if(elems.length==4){
		if(elems[2][3]==4){solved[2]=100+"-("+percents[0]+"+"+percents[1]+" + "+percents[3]+") = <b>"+percents[2]+"</b>%";
		solved[3]=masses[2]+"*"+multipliers[xx-1]+"="+themass[2]+"<br>%"+atoms[xx-1]+"="+themass[2]+" &#247; "+sample[1]+" &#215; 100 = <b>"+percents[3]+"%</b>"
		}
		else {solved[3]=100+" - ("+percents[0]+" + "+percents[1]+" + "+percents[2]+") = <b>"+percents[3]+"</b>%";
		solved[2]=masses[2]+" &#215; "+multipliers[xx-1]+" = "+themass[2]+"<br>%"+atoms[xx-1]+" = "+themass[2]+" &#247; "+sample[1]+" &#215; 100 = <b>"+percents[2]+"%</b>"
		} 
	}
}	
function buildquestion(){
	thequest+="<br><form>";
	for(j=0;j<elems.length;j++)thequest+=elems[j][0]+cell;
	thequest+=thebutton;
	showquest(thequest)
}
function answer(form){
	if(tried==1)alert("You've done this one. Get a new problem!");
	else{
	if(tried==2){totl++;document.forms[0].total.value=totl}
	ok=0	
	attempts++
	for(j=0;j<percents.length;j++){
		if(form.elements[j].value<.95*percents[j]|| form.elements[j].value>1.05*percents[j])ok++;
	}
	if(ok==0){
		tried=1
		document.forms[0].results.value="correct"
		corrt++
		document.forms[0].correct.value=corrt
	}
	else{
		document.forms[0].results.value="incorrect"
		tried=2
	}
}}