Register to reply

Weight combination by percent

by Richay
Tags: combination, percent, weight
Share this thread:
May9-06, 06:43 PM
P: 39
How on earth do you do this?

What percent by weight of Na2S2O3 is Sodium (Na)? (Na, 23; S, 32; 0, 16)

Okay that looks confusing but. The "Na2S2O3" isn't suppose to be spelled like that. It's Na (then a 2 that is haflway beneath the number) And then you repeat with S (lower 2), O and lower 3. It's hard to explaina and i don't know what it's called.

But how do i solve this?
Phys.Org News Partner Science news on
Final pieces to the circadian clock puzzle found
A spray-on light show on four wheels: Darkside Scientific
How an ancient vertebrate uses familiar tools to build a strange-looking head
May9-06, 07:26 PM
P: 30
I take it that the text in parentheses refers to the masses of each of the elements in the compound.

A good start would be to calculate the total mass of the compound, keeping in mind the fact that there are different numbers of each element in the compound (i.e. there are 2 sodium ions, etc.).
May18-06, 09:35 PM
P: 39
How do i calculate it though? I don't understand the 2,2,&3 that belong to Na,S,&O

May18-06, 09:38 PM
PF Gold
dav2008's Avatar
P: 621
Weight combination by percent

Na2S2O3 means that the given molecule/unit (Sodium thiosulfate) is composed of two atoms of Na, two atoms of S, and three atoms of O.

By looking at a periodic table (or the values that are given to you) you can realize that one mole of Na has a mass of 23 grams. One mole of S has a mass of 32 grams. One mole of O has a mass of 16 grams.
May19-06, 02:16 PM
P: 39
I figured out it's 29%

Register to reply

Related Discussions
Percent acetic acid by weight Biology, Chemistry & Other Homework 4
Percent hydrolysis/percent ionazation Biology, Chemistry & Other Homework 1
Percent of Salt by Weight Precalculus Mathematics Homework 4
Rotational weight vs. dead weight Classical Physics 5