<!-- start hiding
//Written by Manuel Villanueva based on script by Mark Earll
function percent_ionized(form) {
if (form.charge[0].checked) {   

var answer = 100 / (1 + Math.pow(10, (1 * (form.ph.value - form.pka.value))));
}
else {
var answer = 100 / (1 + Math.pow(10, (-1 * (form.ph.value - form.pka.value)))) ;
}
form.answer.value = Math.round(10*answer)/10;

//alert
if((form.ph.value==null)||(form.ph.value=="")||(isNaN(form.ph.value))){
alert('Please enter a pH with numbers only. Use a period for decimal place.');
form.ph.focus();
form.ph.select();
return false
}
//alert
if((form.pka.value==null)||(form.pka.value=="")||(isNaN(form.pka.value))){
alert('Please enter a Pka with numbers only. Use a period for decimal place.');
form.pka.focus();
form.pka.select();
return false
}
}
// end hiding -->