Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: timus221 on October 16, 2017, 09:31:50 AM

Title: Product mass
Post by: timus221 on October 16, 2017, 09:31:50 AM

We have 5g of SiO2 and 25g 30% solution of NaOH. Calculate a mass of product. Please help

SiO2+2NaOH =Na2SiO3+H2O

Title: Re: Product mass
Post by: Arkcon on October 16, 2017, 10:23:19 AM

Greetings, timus221:, I'd like to welcome you and all the new students to the Chemical Forums.  But I'd like to ask you to trouble yourself to read our Forum Rules{click} (http://www.chemicalforums.com/index.php?topic=65859.0). You already accepted them when you signed up for our forum, and they apply to you, whether you agree with them or not, or even if you're unaware of them. 

Our rules specify that we want to see your work, and then, we want to give you hints, so that you learn for yourself.  It doesn't matter if you're a new student, or a dedicated amateur, we need to know what you know, and what you think, so we know what level you're at, so we can give useful hints, so your knowledge can grow.   

Let's get started:

Quote from: timus221 on October 16, 2017, 09:31:50 AM

We have 5g of SiO2 and 25g 30% solution of NaOH. Calculate a mass of product. Please help

SiO2+2NaOH =Na2SiO3+H2O

You've been given an equation, that relates products to reactants.  You've been given mass, of reactants, and need mass of products.  But the units of your equation aren't mass.  You will have to convert back and forth.  You will also have to be sure you have enough of both reactants, you can only get as much product as you have enough reactant -- but which one do you have the least of?

There are tasks usually covered in class notes and text books, before these problems are assigned.  Why not try a few of the steps suggested, and show us what you're able to figure out?

Title: Re: Product mass
Post by: timus221 on October 16, 2017, 10:35:41 AM

Ok so in my view it will be :

firstly mass of NaOH 0,3*25g=7,5g

I have to check the insufficiency of reactant:

SiO2+2NaOH =Na2SiO3+H2O

5g-----------xg
60g/mol----80g/mol (NaOH)

x=6,67g so there is excess of NaOH , so

5g------------yg (Na2SiO3)
60g/mol-----122g/mol (Na2SiO3)

y=10,17g

Is it correct ?

Title: Re: Product mass
Post by: Borek on October 16, 2017, 03:12:37 PM

Quote from: timus221 on October 16, 2017, 10:35:41 AM

5g------------yg (Na2SiO3)
60g/mol-----122g/mol (Na2SiO3)

y=10,17g

Is it correct ?

Looks OK.