// JavaScript Document
thepage="84 - Empirical Formulas"
//globals
//11/20/02-updated netscape 7
refnumber=150
cell="<input class='text' type=text size=2 value=''>"
thebutton="<br><input type=button onClick='answer(this.form)' value='Check Answer'>"
corrt=0
attempts=0
tried=0
totl=0
carbons=0
hydrogens=0
oxygens=0
nitrogens=0
chlorines=0
bromines=0
metals=0
elems=0
fracts=0
ratios=0
test=0
themass=0
newnumbers=0
key=0
factor=0
percents=0
formula=""
gfw=0
catsub=""
ansub=""
theanswer=""
function repelement(name,sym,an,mass,val1,val2){
	this.name=name
	this.sym=sym
	this.an=an
	this.mass=mass
	this.val1=val1
	this.val2=val2
	}
function metal(name,sym,an,mass,chg1,chg2){
	this.name=name
	this.sym=sym
	this.an=an
	this.mass=mass
	this.chg1=chg1
	this.chg2=chg2
}
function polyion(name,sym,chg){
	this.name=name
	this.sym=sym
	this.chg=chg
}
reps=new Array()
reps[1]=new repelement("hydrogen","H",1,1.0079,1,1)
reps[2]=new repelement("carbon","C",6,12.011,4,4)
reps[3]=new repelement("nitrogen","N",7,14.0067,3,3)
reps[4]=new repelement("oxygen","O",8,15.9994,3,3)
reps[5]=new repelement("phosphorous","P",15,30.97376,3,5)
reps[6]=new repelement("sulfur","S",16,32.066,32,2,4)
reps[7]=new repelement("fluorine","F",9,18.99840,1,1)
reps[8]=new repelement("chlorine","Cl",17,35.453,1,1)
reps[9]=new repelement("bromine","Br",35,79.904,1,1)
reps[10]=new repelement("iodine","I",53,126.9045,1,1)
mets=new Array()
mets[1]=new metal("lithium","Li",3,6.941,1,1)
mets[2]=new metal("beryllium","Be",4,9.01218,2,2)
mets[3]=new metal("sodium","Na",11,22.98977,1,1)
mets[4]=new metal("magnesium","Mg",12,24.305,2,2)
mets[5]=new metal("aluminum","Al",13,26.98154,3,3)
mets[6]=new metal("potassium","K",19,39.098,1,1)
mets[7]=new metal("calcium","Ca",20,40.08,2,2)
mets[8]=new metal("scandium","Sc",21,44.9559,3,3)
mets[9]=new metal("titanium","Ti",22,47.88,4,4)
mets[10]=new metal("vanadium","V",23,50.9415,5,4)
mets[11]=new metal("chromium","Cr",24,51.996,6,3)
mets[12]=new metal("manganese","Mn",25,54.9380,4,2)
mets[13]=new metal("iron","Fe",26,55.847,2,3)
mets[14]=new metal("cobalt","Co",27,58.9332,2,3)
mets[15]=new metal("nickel","Ni",28,58.69,2,2)
mets[16]=new metal("copper","Cu",29,63.546,2,1)
mets[17]=new metal("zinc","Zn",30,65.39,2,2)
mets[18]=new metal("rubidium","Rb",37,85.4678,1,1)
mets[19]=new metal("strontium","Sr",38,87.62,2,2)
mets[20]=new metal("molybdenum","Mo",42,95.94,6,4)
mets[21]=new metal("ruthenium","Ru",44,101.07,3,4)
mets[22]=new metal("rhodium","Rh",45,102.9055,3,4)
mets[23]=new metal("palladium","Pd",46,106.42,2,2)
mets[24]=new metal("silver","Ag",47,107.868,1,1)
mets[25]=new metal("cadmium","Cd",48,112.411,2)
mets[26]=new metal("indium","In",49,114.82,3,3)
mets[27]=new metal("tin","Sn",50,118.710,4,2)
mets[28]=new metal("antimony","Sb",51,121.75,3,5)
mets[29]=new metal("cesium","Cs",55,132.9054,1,1)
mets[30]=new metal("barium","Ba",56,137.27,2,2)
mets[31]=new metal("tungsten","W",74,183.85,6,4)
mets[32]=new metal("rhenium","Re",75,186.207,4,2)
mets[33]=new metal("osmium","Os",76,190.2,3,4)
mets[34]=new metal("iridium","Ir",77,192.22,2,3)
mets[35]=new metal("platinum","Pt",78,195.08,2,4)
mets[36]=new metal("gold","Au",79,196.9665,1,3)
mets[37]=new metal("mercury","Hg",80,200.59,1,2)
mets[38]=new metal("thallium","Tl",81,204.383,3,1)
mets[39]=new metal("lead","Pb",82,207.2,2,2)
anion=new Array()
comp=new Array()
anion[1]=new polyion("carbonate","CO<sub>3</sub>",2)
comp[1]=new Array(2,1,4,3)
anion[2]=new polyion("hydroxide","OH",1)
comp[2]=new Array(4,1,1,1)
anion[3]=new polyion("nitrate","NO<sub>3</sub>",1)
comp[3]=new Array(3,1,4,3)
anion[4]=new polyion("nitrite","NO<sub>2</sub>",1)
comp[4]=new Array(3,1,4,2)
anion[5]=new polyion("sulfate","SO<sub>4</sub>",2)
comp[5]=new Array(6,1,4,4)
anion[6]=new polyion("sulfite","SO<sub>3</sub>",2)
comp[6]=new Array(6,1,4,3)
anion[7]=new polyion("cyanide","CN",1)
comp[7]=new Array(2,1,3,1)
anion[8]=new polyion("phosphate","PO<sub>4</sub>",3)
comp[8]=new Array(5,1,4,4)
anion[9]=new polyion("bicarbonate","HCO<sub>3</sub>",1)
comp[9]=new Array(1,1,2,1,4,3)
anion[10]=new polyion("chlorite","ClO<sub>2</sub>",1)
comp[10]=new Array(8,1,4,2)
anion[11]=new polyion("thiosulfate","S<sub>2</sub>O<sub>3</sub>",2)
comp[11]=new Array(6,2,4,3)
anion[12]=new polyion("hypochlorite","ClO",1)
comp[12]=new Array(8,1,4,1)
anion[13]=new polyion("chlorate","ClO<sub>3</sub>",1)
comp[13]=new Array(8,1,4,3)
anion[14]=new polyion("phosphite","PO<sub>3</sub>",3)
comp[14]=new Array(5,1,4,3)
function clear(){
	document.forms[0].results.value=""
	attempts=0
	tried=0
	clearansspot()
}
introphrase="A compound has the following mass% composition. Determine the empirical formula, enter the values for each element in the appropriate cell and press 'Check Answer.'<br>"
ansphrase=new Array("First,assume you have a sample with a mass of 100 and convert all of the percentages directly into grams.Then, divide each of the resultant masses by the appropriate gaw:<br><br>","Divide all of the resultant values(which are moles) by the lowest to get the first set of ratios:<br><br>","Since the resultant values are all nearly integral, the empirical formula is:<br>","Since all of the values are not 'near integers', further adjustment is needed")
function startit(){
	totl++
	document.forms[0].total.value=totl
	clear()
	if(Math.random()>.4)organic()
	else inorganic()
}
function organic(){
	elems=new Array()
	themass=new Array()
	percents=new Array()
	c=2+Math.floor(5*Math.random())
	h=2*c+2
	h=h-removeh(h/2)
	elems[0]=new Array(reps[2].sym,reps[2].mass,c)
	elems[1]=new Array(reps[1].sym,reps[1].mass,h)
	option=Math.ceil(8*Math.random())
	if(option==1){
		n=Math.ceil(2*Math.random())
		elems[elems.length]=new Array(reps[3].sym,reps[3].mass,n)
		h++
		}
	if(option==2 || option==7 ||option==8){
		o=Math.ceil(2*Math.random())
		elems[elems.length]=new Array(reps[4].sym,reps[4].mass,o)
		}
	if(option==3 || option==7){
		s=Math.ceil(2*Math.random())
		elems[elems.length]=new Array(reps[6].sym,reps[6].mass,s)
		}
	if(option==4){
		p=Math.ceil(2*Math.random())
		elems[elems.length]=new Array(reps[5].sym,reps[5].mass,p)
		}
	if(option>6){
		hal=Math.ceil(2*Math.random())
		whichhal=7+Math.floor(4*Math.random())
		elems[elems.length]=new Array(reps[whichhal].sym,reps[whichhal].mass,hal)
		h--
		}
	
	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);
	buildanswer(elems)
	buildquest(formula)
	}	
function removeh(x){
	drop=Math.floor(Math.random()*x)
	if(drop%2!=0)drop+=1
	return drop
}
function inorganic(){
	elems=new Array()
	themass=new Array()
	percents=new Array()
	whichmetal=Math.ceil(39*Math.random())
	charge=Math.ceil(2*Math.random())
	catchg=mets[whichmetal]['chg'+charge]
	if(Math.random()>.6){
		counterkey=1
		theanion=repion()
		theanion<7?anchg=2:anchg=1;
	}
	else{
		counterkey=2
		theanion=Math.ceil(14*Math.random())
		anchg=anion[theanion].chg
	}
	if(catchg==anchg)catsub=ansub=1;
	else getsubs(catchg,anchg)
	elems[0]=new Array(mets[whichmetal].sym,mets[whichmetal].mass,catsub)
	formula=""
	gfw=0
	formula+=mets[whichmetal].sym;
	if(catsub!=1)formula+=("<sub>"+catsub+"</sub>");
	themass[0]=catsub*mets[whichmetal].mass
	gfw+=themass[0]
	if(counterkey==1){
		elems[1]=new Array(reps[theanion].sym,reps[theanion].mass,ansub)
		formula+=reps[theanion].sym;
		if(ansub!=1)formula+=("<sub>"+ansub+"</sub>");
		themass[1]=ansub*reps[theanion].mass
		gfw+=themass[1]
		}
	else{
		ansub==1?formula+=anion[theanion].sym:formula+="("+anion[theanion].sym+")<sub>"+ansub+"</sub>";
		for(j=0;j<comp[theanion].length;j=j+2){
			spot=comp[theanion][j]
			elems[elems.length]=new Array(reps[spot].sym,reps[spot].mass,ansub*comp[theanion][j+1])
			themass[themass.length]=ansub*comp[theanion][j+1]*reps[spot].mass
			gfw+=themass[themass.length-1]
		}
	}
	for(var j=0;j<themass.length;j++)percents[j]=number(100*themass[j]/gfw,3,3);
	gfw=number(gfw,4,3)
	buildanswer(elems)
	buildquest(formula)
}
function repion(){
	theanion=5
	while(theanion==5)theanion=4+Math.floor(7*Math.random());
	return theanion
	}
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 buildquest(formula){
	thequest=introphrase;
	for(j=0;j<elems.length;j++)thequest+="<b>"+elems[j][0]+": </b>"+percents[j]+"%<br>";
	thequest+="<form>"
	for(j=0;j<elems.length;j++)thequest+=elems[j][0]+cell;
	thequest+=(thebutton+"</form>");
	showquest(thequest)
}
function buildanswer(elems){
	theanswer=ansphrase[0]
	getfracts(elems)
	getnumbers(elems)
	for(k=0;k<percents.length;k++)theanswer+="<b>"+elems[k][0]+":</b>"+percents[k]+"/"+elems[k][1]+"="+fracts[k]+"<br>";
	theanswer+=ansphrase[1]
	for(var j=0;j<percents.length;j++)theanswer+="<b>"+elems[j][0]+":</b>"+fracts[j]+"/"+fracts[fracts.length-1]+"="+ratios[j]+"<br>";
	if(test==0){
		theanswer+="These values are all near integers, so they can be rounded."
		formula=""
		for(var j=0;j<ratios.length;j++){
			ratios[j]=Math.round(ratios[j])
			ratios[j]==1?formula+=elems[j][0]:formula+=elems[j][0]+"<sub>"+ratios[j]+"</sub>";
		}
	}
	else{
		theanswer+="Since the values are not all near integers, they are further adjusted yielding by multiplying all the values by "+factor;
		formula=""
		for(var j=0;j<ratios.length;j++){
		ratios[j]=Math.round(factor*ratios[j])
			ratios[j]!=1?formula+=elems[j][0]+"<sub>"+ratios[j]+"</sub>":formula+=elems[j][0];
		}
	}
	theanswer+="<br>"+formula	
}
function getfracts(elems){
	fracts=new Array()
	ratios=new Array()
	for(var j=0;j<percents.length;j++){
		fracts[j]=number(percents[j]/elems[j][1],4,3)
	}
	theleast=1*fracts[0]
	for(j=1;j<fracts.length;j++){
		if(1*fracts[j]<theleast)theleast=fracts[j];
		}
	fracts[fracts.length]=theleast
	for(var j=0;j<percents.length;j++){
		ratios[j]=number(fracts[j]/fracts[fracts.length-1],4,3)
	}
	checkratios(ratios)
}
function checkratios(ratios){
	test=0
	poor=""
	for(var j=0;j<ratios.length;j++){
		if((1*ratios[j])%1>.2 & (1*ratios[j])%1<.8){test=1;poor=j}
	}
	if(test==1)fixthem(ratios,poor)
	}
function fixthem(ratios,poor){
	key=(1*ratios[poor])%1
	if(key<.22)factor=5;
		if(key<.28)factor=4;
	 		else if(key<.35)factor=3;
				else if(key<.42)factor=5;
					else if(key<.52)factor=2;
						else if(key<.69)factor=3;
							else if(key<.78)factor=4;
	}	
function getnumbers(elems){
	thenumbers=new Array()
	newnumbers=new Array()
	for(var j=0;j<elems.length;j++)thenumbers[j]=elems[j][2];
	themost=thenumbers[0]
	for(var j=1;j<5;j++){if(thenumbers[j]>themost)themost=thenumbers[j]};
	themost=Math.floor(themost/2)
	tested=new Array()
	for(k=2;k<=themost;k++){
		allowed=0
		for(var j=0;j<5;j++){if(thenumbers[j]%k!=0)allowed++};
		if(allowed==0)tested[tested.length]=k;
	}
	for(var j=0;j<tested.length;j++){
		if(tested[j]!=1){
		for(var k=0;k<thenumbers.length;k++){
			newnumbers[k]=thenumbers[k]/tested[j]
		}}
	}
}
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	
	for(j=0;j<ratios.length;j++){
		if(form.elements[j].value!=ratios[j])ok++;
	}
	if(ok==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
	}}
}