thepage="Nernst Equation(144)"
//11/20/02-updated netscape 7
refnumber=187
corrt=0
tried=0
totl=0
equations=""
theanswr=0
which=0
thesteps=new Array()
thecmpds=tablecmpds=""
front=""
back=""
coeffs=""
factor=""
theratio=valueratio=0
W=H=0
attempts=0
type=0
first=3
second=0
reaction=""
balreaction=""
theconcs=""
thetable=""
theE=theQ=thelog=0
num=denom=valuenum=valuedenom=""
terms=0
netes=0
concset=new Array("0.10","0.20","0.40","0.05","0.80","1.0","0.010")
soltype=new Array("<b> (acidic)</b>","<b> (basic)</b>")
acidtype=new Array("H<sup>+</sup>","OH<sup>-</sup>")
water="H<sub>2</sub>O(l)"
thecell="<input type=text size=2 value=''>"
thebutton="<input type=button value='Check Answer' onClick='answer(this.form)'>"
thenernst="E=E<sup>o</sup>-0.0257/n*lnQ"
phasesym=new Array("(aq)","(g)","(s)","(l)")
phrases=new Array("The Nernst Equation has the general form:<br>","First, the equation is rewritten to fit the reaction under study.<br>","Then, the values for E<sup>o</sup>,n and the concentration terms are entered.<br>","Q is evaluated<br>","The terms are solved and combined.<br>","Finally, E is calculated<br>")
//halfrxn-reduction couples and the electrons 
halfrxn=new Array()
//information needed-coeffs,followed by H+ and H20 for acid, followed by OH-,H20 for base.If //sign is +its a reagent 
dataset=new Array()
phase=new Array()
halfrxn[0]=new Array("Fe+3","Fe+2",1)
dataset[0]=new Array(1,1,0,0,0,0)
phase[0]=new Array(0,0)
halfrxn[1]=new Array("F2","F-",2)
dataset[1]=new Array(1,2,0,0,0,0)
phase[1]=new Array(1,0)
halfrxn[2]=new Array("O3","O2",2)
dataset[2]=new Array(1,1,2,1,-2,-1)
phase[2]=new Array(1,1)
halfrxn[3]=new Array("PbO2","Pb+2",2)
dataset[3]=new Array(1,1,4,2,-4,-2)
phase[3]=new Array(2,0)
halfrxn[4]=new Array("Cl2","Cl-",2)
dataset[4]=new Array(1,2,0,0,0,0)
phase[4]=new Array(1,0)
halfrxn[5]=new Array("Mg+2","Mg",2)
phase[5]=new Array(0,2)
dataset[5]=new Array(1,1,0,0,0,0)
halfrxn[6]=new Array("Al+3","Al",3)
dataset[6]=new Array(1,1,0,0,0,0)
phase[6]=new Array(0,2)
halfrxn[7]=new Array("Cr+2","Cr",2)
dataset[7]=new Array(1,1,0,0,0,0)
phase[7]=new Array(0,2)
halfrxn[8]=new Array("MnO4-","Mn+2",5)
dataset[8]=new Array(1,1,8,4,-8,-4)
phase[8]=new Array(0,0)
halfrxn[9]=new Array("Cr2O7-2","Cr+3",6)
dataset[9]=new Array(1,2,14,7,-14,-7)
phase[9]=new Array(0,0)
halfrxn[10]=new Array("ClO2-","ClO-",2)
dataset[10]=new Array(1,1,2,1,-2,-1)
phase[10]=new Array(0,0)
halfrxn[11]=new Array("ClO4-","Cl-",8)
dataset[11]=new Array(1,1,8,4,-4,-8)
phase[11]=new Array(0,0)
halfrxn[12]=new Array("PbO2","PbO",2)
dataset[12]=new Array(1,1,2,1,-1,-2)
phase[12]=new Array(2,2)
halfrxn[13]=new Array("Au+3","Au+",2)
phase[13]=new Array(0,0)
dataset[13]=new Array(1,1,0,0,0,0)
halfrxn[14]=new Array("MnO4-","MnO2",3)
phase[14]=new Array(0,2)
dataset[14]=new Array(1,1,4,2,-4,-2)
halfrxn[15]=new Array("IO3-","I2",10)
dataset[15]=new Array(2,1,12,6,-6,-12)
phase[15]=new Array(0,0)
halfrxn[16]=new Array("ClO-","Cl-",2)
dataset[16]=new Array(1,1,2,1,-2,-1)
phase[16]=new Array(0,0)
halfrxn[17]=new Array("Fe2O3","Fe",6)
dataset[17]=new Array(1,2,6,3,99,99)
phase[17]=new Array(2,2)
halfrxn[18]=new Array("Br2","Br-",2)
dataset[18]=new Array(1,2,0,0,0,0)
phase[18]=new Array(0,0)
halfrxn[19]=new Array("Ag+","Ag",1)
dataset[19]=new Array(1,1,0,0,0,0)
phase[19]=new Array(0,2)
halfrxn[20]=new Array("S2O8-2","SO4-2",2)
dataset[20]=new Array(1,2,0,0,0,0)
phase[20]=new Array(0,0)
halfrxn[21]=new Array("SO4-2","SO2",2)
dataset[21]=new Array(1,1,4,2,-4,-2)
phase[21]=new Array(0,0)
halfrxn[22]=new Array("MnO2","Mn+2",2)
dataset[22]=new Array(1,1,4,2,-4,-2)
phase[22]=new Array(2,0)
halfrxn[23]=new Array("NO3-","NO",3)
dataset[23]=new Array(1,1,4,2,-4,-2)
phase[23]=new Array(0,0)
halfrxn[24]=new Array("I2","I-",2)
dataset[24]=new Array(1,2,0,0,0,0)
phase[24]=new Array(0,0)
halfrxn[25]=new Array("Sn+4","Sn+2",2)
dataset[25]=new Array(1,1,0,0,0,0)
phase[25]=new Array(0,0)
halfrxn[26]=new Array("Sn+2","Sn",2)
dataset[26]=new Array(1,1,0,0,0,0)
phase[26]=new Array(0,2)
halfrxn[27]=new Array("BrO3-","Br2",10)
dataset[27]=new Array(2,1,12,6,-6,-3)
phase[27]=new Array(0,0)
halfrxn[28]=new Array("VO2+","VO+2",1)
dataset[28]=new Array(1,1,2,1,-2-1)
phase[28]=new Array(0,0)
halfrxn[29]=new Array("NO2-","NO",1)
dataset[29]=new Array(1,1,2,1,-2,-1)
phase[29]=new Array(0,0)
halfrxn[30]=new Array("Hg+2","Hg2+2",2)
dataset[30]=new Array(2,1,0,0,0,0)
phase[30]=new Array(0,0)
halfrxn[31]=new Array("Sb2O5","SbO+",4)
dataset[31]=new Array(1,2,6,3,-6,-3)
phase[31]=new Array(2,0)
halfrxn[32]=new Array("I3-","I-",2)
dataset[32]=new Array(1,3,0,0,0,0)
phase[32]=new Array(0,0)
halfrxn[33]=new Array("VO+2","V+3",1)
dataset[33]=new Array(1,1,2,1,-2,-1)
phase[33]=new Array(0,0)
halfrxn[34]=new Array("UO2+2","U+4",2)
dataset[34]=new Array(1,1,4,2,-4,-2)
phase[34]=new Array(0,0)
halfrxn[35]=new Array("BiO+","Bi",3)
dataset[35]=new Array(1,1,2,1,-2,-1)
phase[35]=new Array(0,2)
halfrxn[36]=new Array("SbO+","Sb",3)
dataset[36]=new Array(1,1,2,1,-2,-1)
phase[36]=new Array(0,2)
halfrxn[37]=new Array("SO4-2","SO2",2)
dataset[37]=new Array(1,1,4,2,-4,-2)
phase[37]=new Array(0,0)
halfrxn[38]=new Array("TiO+2","Ti+3",1)
dataset[38]=new Array(1,1,2,1,-2,-1)
phase[38]=new Array(0,0)
halfrxn[39]=new Array("Mo+3","Mo",3)
dataset[39]=new Array(1,1,0,0,0,0)
phase[39]=new Array(0,2)
halfrxn[40]=new Array("H3PO3","H3PO2",2)
dataset[40]=new Array(1,1,2,1,99,99)
phase[40]=new Array(0,0)
halfrxn[41]=new Array("Th+4","Th",4)
dataset[41]=new Array(1,1,0,0,0,0)
phase[41]=new Array(0,2)
halfrxn[42]=new Array("Sb2O3","Sb",6)
dataset[42]=new Array(1,2,6,3,-6,-3)
phase[42]=new Array(2,2)
halfrxn[43]=new Array("H3BO3","B",3)
dataset[43]=new Array(1,1,3,3,99,99)
phase[43]=new Array(0,2)
halfrxn[44]=new Array("AsO2-","As",3)
dataset[44]=new Array(1,1,4,2,-4,-2)
phase[44]=new Array(0,2)
halfrxn[45]=new Array("Be2O3-2","Be",4)
dataset[45]=new Array(1,2,6,3,-6,-3)
phase[45]=new Array(0,2)
halfrxn[46]=new Array("ClO2","ClO2-",1)
dataset[46]=new Array(1,1,0,0,0,0)
phase[46]=new Array(0,0)
halfrxn[47]=new Array("F2O","F-",4)
dataset[47]=new Array(1,2,2,1,-2,-1)
phase[47]=new Array(0,0)
halfrxn[48]=new Array("GeO2","GeO",2)
dataset[48]=new Array(1,1,2,1,-2,-1)
phase[48]=new Array(2,2)
halfrxn[49]=new Array("HgO","Hg",2)
dataset[49]=new Array(1,1,2,1,-2,-1)
phase[49]=new Array(2,2)
halfrxn[50]=new Array("NO3-","NO2",1)
dataset[50]=new Array(1,1,2,1,99,99)
phase[50]=new Array(0,0)
function cleanse(){
	clear()
	document.forms[0].correct.value=0
	document.forms[0].total.value=0
}
function clear(){
	tried=0
	attempts=0
	document.forms[0].results.value=""
	clearansspot()
}
function startit(){
	clear()
	totl++
	document.forms[0].total.value=totl
	Math.random()>.25?type=0:type=1;
	document.forms[0].results.value=""
	first=Math.floor(Math.random()*halfrxn.length)
	theE=0
	while(theE<.10)theE=3*Math.random()
	theE=number(theE,3,3)
	if(Math.random()<.5)theE=-1*theE
	second=first
	while(second==first)second=Math.floor(Math.random()*halfrxn.length)
	if(type==1){
		if(dataset[first][4]==99 || dataset[second][4]==99){totl--,startit()};
		}
	getcmpds(first,second)
	//gethalfs(first,second)
	reaction=""
	reaction=thecmpds[1]+" + "+thecmpds[2]+" => "+thecmpds[3]+" + "+thecmpds[4]+soltype[type]
	getcoeffs(first,second)
}
function getcoeffs(first,second){
	coeffs=new Array(0,dataset[first][0],dataset[second][1],dataset[first][1],dataset[second][0])
	factor=new Array()
	lost=halfrxn[first][2]
	gain=halfrxn[second][2]
	if(lost==gain)factor[0]=factor[1]=1;
	else{
		while(gain%2==0 & lost%2==0){
			gain=gain/2
			lost=lost/2
			}
		while(gain&3==0 & lost%2==0){
			gain=gain/3
			lost=lost/3
			}
	}
	if(lost>gain){
		if((lost%gain)==0){factor[0]=1;factor[1]=lost/gain}
		else{factor[0]=gain;factor[1]=lost}
	}
	else{
		if((gain%lost)==0){factor[0]=gain/lost;factor[1]=1}
		else{factor[0]=gain;factor[1]=lost}
	}
	netes=factor[0]*lost
	H=factor[0]*dataset[first][2+2*type]-factor[1]*dataset[second][2+2*type];
	W=factor[0]*dataset[first][3+2*type]-factor[1]*dataset[second][3+2*type];
	thesteps[6]=""
	terms=new Array()
	H>0?terms[0]=H:terms[5]=Math.abs(H);
	W>0?terms[5]=W:terms[0]=Math.abs(W);
	for(j=1;j<5;j++){
		if(j==1 || j==3)terms[j]=factor[0]*coeffs[j];
		else terms[j]=factor[1]*coeffs[j];
	}
	getconcs(first,second,terms)
	//thesteps[6]=terms[1]+thecmpds[1]+" + "+terms[2]+thecmpds[2]+" => "+terms[3]+thecmpds[3]+" + "+terms[4]+thecmpds[4]
	sterms=new Array()
	for(j=1;j<5;j++)terms[j]>1?sterms[j]=terms[j]:sterms[j]="";
	thesteps[6]=sterms[1]+thecmpds[1]+" + "+sterms[2]+thecmpds[2]+" => "+sterms[3]+thecmpds[3]+" + "+sterms[4]+thecmpds[4]
	if(H!=0){
		Math.abs(H)>1?sH=Math.abs(H):sH="";
		H>0?thesteps[6]=sH+thecmpds[0]+" + "+thesteps[6]:thesteps[6]+=" + "+sH+thecmpds[0];
		hterm=tablecmpds[0]
		if(Math.abs(H)>1)hterm+=("<sup>"+Math.abs(H)+"</sup>")
		theconcs[theconcs.length]=new Array(tablecmpds[0],concset[Math.floor(Math.random()*concset.length)],hterm,-H);
		concH="["+theconcs[theconcs.length-1][1]+"]"
		if(Math.abs(H)>1)concH+="<sup>"+Math.abs(H)+"</sup>"
		H>0?denom+=hterm:num+=hterm
		H>0?valuedenom+=concH:valuenum+=concH	
	}
	if(W!=0){
		Math.abs(W)>1?sW=Math.abs(W):sW="";
		W>0?thesteps[6]+=" + "+sW+thecmpds[5]:thesteps[6]=sW+thecmpds[5]+" + "+thesteps[6];
	}
	theratio=num+"/"+denom
	valueratio=valuenum+"/"+valuedenom
	balreaction=thesteps[6]+"   E<sup>o</sup>= "+theE+"<b>V</b>"
	buildquest(terms)	
	buildanswer()		
}
function getcmpds(first,second){
	thecmpds=new Array()
	tablecmpds=new Array()
	tablecmpds[0]=acidtype[type]
	tablecmpds[1]=completeformula(halfrxn[first][0])
	tablecmpds[2]=completeformula(halfrxn[second][1])
	tablecmpds[3]=completeformula(halfrxn[first][1])
	tablecmpds[4]=completeformula(halfrxn[second][0])
	tablecmpds[5]=water
	thecmpds[0]=acidtype[type]+"(aq)"
	thecmpds[1]=tablecmpds[1]+phasesym[phase[first][0]]
	thecmpds[2]=tablecmpds[2]+phasesym[phase[second][1]]
	thecmpds[3]=tablecmpds[3]+phasesym[phase[first][1]]
	thecmpds[4]=tablecmpds[4]+phasesym[phase[second][0]]
	thecmpds[5]=water
	for(j=0;j<6;j++)tablecmpds[j]="["+tablecmpds[j]+"]"
}
function getconcs(first,second,terms){
	num=denom=""
	valuenum=valuedenom=""
	conc=new Array()
	theconcs=new Array()
	thetable="<br>"
	if(phase[first][0]<2){theconcs[theconcs.length]=new Array(tablecmpds[1],concset[Math.floor(Math.random()*concset.length)],tablecmpds[1],-1);
		valuedenom+="["+theconcs[theconcs.length-1][1]+"]"
		if(terms[1]>1){
			theconcs[theconcs.length-1][2]=tablecmpds[1]+"<sup>"+terms[1]+"</sup>"
			theconcs[theconcs.length-1][3]=-terms[1]
			valuedenom+="<sup>"+terms[1]+"</sup>"		
		}
		denom+=theconcs[theconcs.length-1][2]
		}
	if(phase[first][1]<2){theconcs[theconcs.length]=new Array(tablecmpds[3],concset[Math.floor(Math.random()*concset.length)],tablecmpds[3],1);
		valuenum+="["+theconcs[theconcs.length-1][1]+"]"
		if(terms[3]>1){
			theconcs[theconcs.length-1][2]=tablecmpds[3]+"<sup>"+terms[3]+"</sup>"
			theconcs[theconcs.length-1][3]=terms[3]	
			valuenum+="<sup>"+terms[3]+"</sup>"
		}
		num+=theconcs[theconcs.length-1][2]
		}
	if(phase[second][0]<2){theconcs[theconcs.length]=new Array(tablecmpds[4],concset[Math.floor(Math.random()*concset.length)],tablecmpds[4],1);
		valuenum+="["+theconcs[theconcs.length-1][1]+"]"
		if(terms[4]>1){
			theconcs[theconcs.length-1][2]=tablecmpds[4]+"<sup>"+terms[4]+"</sup>"
			theconcs[theconcs.length-1][3]=terms[4]
			valuenum+="<sup>"+terms[4]+"</sup>"
		}
		num+=theconcs[theconcs.length-1][2]
		}
	if(phase[second][1]<2){theconcs[theconcs.length]=new Array(tablecmpds[2],concset[Math.floor(Math.random()*concset.length)],tablecmpds[2],-1);
		valuedenom+="["+theconcs[theconcs.length-1][1]+"]"
		if(terms[2]>1){
			theconcs[theconcs.length-1][2]=tablecmpds[2]+"<sup>"+terms[2]+"</sup>"
			theconcs[theconcs.length-1][3]=-terms[2]
			valuedenom+="<sup>"+terms[2]+"</sup>"	
		}
		denom+=theconcs[theconcs.length-1][2]
		}
	if(denom==""){denom="1";valuedenom="1"}
	if(num==""){num="1";valuenum="1"}
}
function buildquest(){
	thequest=""
	for(j=0;j<theconcs.length;j++)thetable+=theconcs[j][0]+":"+theconcs[j][1]+"<b>M</b><br>";
	thequest=balreaction+thetable
	showquest(thequest)
}
function buildanswer(){
	theanswer=""
	theQ=calcQ()
	equations=new Array()
	equations[0]=thenernst
	equations[1]="E="+theE+"-0.0257/"+netes+"*ln("+theratio+")"
	equations[2]="E="+theE+"-0.0257/"+netes+"*ln("+valueratio+")"
	equations[3]="E="+theE+"-0.0257/"+netes+"*ln("+theQ+")"
	equations[4]="E="+theE+"-"+number(.0257/netes,3,3)+"*"+number(thelog,3,3)
	solvedvalue=theE-1*number(.0257/netes*thelog,3,3)
	equations[5]="E="+number(solvedvalue,3,3)
	theanswr=solvedvalue
	solved=new Array()
	for(var j=0;j<theconcs.length;j++){
		solved[j]=theconcs[j][2]+"=>["+theconcs[j][1]+"]";
		if(Math.abs(theconcs[j][3])>1)solved[j]+="<sup>"+Math.abs(theconcs[j][3])+"</sup>";
		solved[j]+="="+number(Math.pow(1*theconcs[j][1],Math.abs(theconcs[j][3])),2,3)
	}
	//theanswer=reaction+"<br>"+phrases[0]
	for( var j=0;j<6;j++){
		//if(j==2)theanswer+=phrases[1];
		//if(j==4)theanswer+=phrases[2];
		//if(j==6)theanswer+=phrases[3];
		theanswer+=phrases[j]+equations[j]+"<br>";
	}	
}
function calcQ(){
	theQ=1
	for(var j=0;j<theconcs.length;j++)theQ*=Math.pow(theconcs[j][1],theconcs[j][3])
	thelog=Math.log(theQ)
	if(theQ>100 || theQ<.01)return number(theQ,3,2);
	else return number(theQ,3,3)
}					
function answer(ans){
	attempts++
	if(tried==1){alert("You've already done this problem. Get a new one!")}
	else{kk=0
	if(tried==2){totl++;document.forms[0].total.value=totl}
	if(theanswr<0){
		if(ans>1.05*theanswr & ans<.95*theanswr){
    		kk=1}}
	else{
		if(ans<1.05*theanswr & ans>.95*theanswr){
    	kk=1}
	}
	if(kk==1){
    		document.forms[0].results.value="correct"
    		corrt++
    		document.forms[0].correct.value=corrt
    		tried=1
	}
	else{
    		tried=2
    	document.forms[0].results.value="incorrect"}
	}	
}