// JavaScript Document
thepage="Intro to pH - pA and pB"
//updated 12/02/02-netscape 7
//global variables
refnumber=127
corrt=0
tried=0
totl=0
theanswer=0
thesolution=0
alldata=0
solved=0
shown=0
symbols=new Array("","A","B","pA","pB")
equation=new Array()
equation[0]=symbols[1]+"=10<sup>-"+symbols[3]+"</sup>"//H=10^-pA
equation[1]=symbols[2]+"=10<sup>-"+symbols[4]+"</sup>"//OH=10^-p0H
equation[2]=symbols[1]+"=10<sup>-14</sup>/"+symbols[2]//H=10^-14/OH
equation[3]=symbols[2]+"=10<sup>-14</sup>/"+symbols[1]//H=10^-14/OH
equation[4]=symbols[3]+"=-log"+symbols[1]//pA=-logH
equation[5]=symbols[4]+"=-log"+symbols[2]//p0H=-logOH
equation[6]=symbols[3]+"=14-"+symbols[4]//pA=14-pB
equation[7]=symbols[4]+"=14-"+symbols[3]//pB=14-pA
eqnsets=new Array()
eqnsets[0]=new Array("")
eqnsets[1]=new Array(3,4,5)
eqnsets[2]=new Array(2,4,5)
eqnsets[3]=new Array(7,0,1)
eqnsets[4]=new Array(6,0,1)
function clear(){
	for(j=1;j<5;j++)document.forms[0].elements[j].value="";
	document.forms[0].results.value=""
	attempts=0
	tried=0
	clearansspot()
}
function startit(){
	alldata=new Array()
	clear()
	totl++
	document.forms[0].total.value=totl
	alldata[3]=0
	while(alldata[3]<1)alldata[3]=12*Math.random();
	alldata[3]=number(alldata[3],3,3)
	alldata[4]=number((14-alldata[3]),3,3)
	alldata[1]=Math.pow(10,-alldata[3])
	alldata[2]=Math.pow(10,-alldata[4])
	alldata[1]=number(alldata[1],3,1)
	alldata[2]=number(alldata[2],3,1)	
	makeproblem()
	getsolutions()
	buildanswer()
}
function makeproblem(){
	shown=Math.ceil(4*Math.random())
	document.forms[0].elements[shown].value=alldata[shown]
	}
function getsolutions(){
	solved=new Array()
	solved[0]="10<sup>-"+alldata[3]+"</sup>="+alldata[1]//H=10^-pA
	solved[1]="10<sup>-"+alldata[4]+"</sup>="+alldata[2]//OH=10^-p0H
	solved[2]="10<sup>-14</sup>/("+alldata[2]+")="+alldata[1]//H=10^-14/OH
	solved[3]="10<sup>-14</sup>/("+alldata[1]+")="+alldata[2]//H=10^-14/OH
	solved[4]="-log("+alldata[1]+")="+alldata[3]//pA=-logH
	solved[5]="-log("+alldata[2]+")="+alldata[4]//p0H=-logOH
	solved[6]="14-"+alldata[4]+"="+alldata[3]//pA=14-pB
	solved[7]="14-"+alldata[3]+"="+alldata[4]//pB=14-pA
}
function buildanswer(){
	theeqn=geteqn()
	theanswer="When the "+symbols[shown]+" is given, the other values are readily determined by the series of steps shown below.<br>"
	theanswer+=theeqn
}
function geteqn(which){
	theeqn="<br>"
	for(var j=0;j<eqnsets[shown].length;j++)theeqn+=equation[eqnsets[shown][j]]+"   <B>=></B>   "+solved[eqnsets[shown][j]]+"<br>";
	return theeqn
	}
function answer(form){
	if(tried==1)alert("You've already done this one! Get a new problem");
	else{
		test=0
		attempts++
		if(tried==2){totl++;document.forms[0].total.value=totl};
		for(j=1;j<=4;j++){
			if(form.elements[j].value<.95*alldata[j] || form.elements[j].value>1.05*alldata[j])test++;
		}
		if(test==0){
			document.forms[0].results.value="correct"
			corrt++
			document.forms[0].correct.value=corrt
			tried=1
			}
		else{
			document.forms[0].results.value="incorrect"
			tried=2
			}
		}
}