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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: John11 on June 22, 2021, 02:50:35 AM

Title: Composition Determination of a Mixture
Post by: John11 on June 22, 2021, 02:50:35 AM

You are given a sample that contains a mixture of the following two arsenic-containing minerals: paakkonenite (Sb2AsS2) and orpiment (As2S3). You start with a sample of this mixture that has a mass of 98.49 grams. You perform a reaction that converts the arsenic (As) in these minerals into the form calcium arsenate (Ca3(AsO4)2), and 62.46 grams of this product are obtained.
What is the percent by mass of paakkonenite in the original sample?

I don't understand the steps that need to be taken in order to solve this problem. Any help or clarity is appreciated.

Title: Re: Composition Determination of a Mixture
Post by: Borek on June 22, 2021, 12:48:15 PM

Please read the forum rules (https://www.chemicalforums.com/index.php?topic=65859.0). You have to show your attempts at answering the question/solving the problem to receive help, it is a forum policy.

Hint: you have two unknowns: mass of paakkonenite and orpiment. Information given allows you to write two equations.

Title: Re: Composition Determination of a Mixture
Post by: Orcio_87 on June 25, 2021, 03:58:23 PM

@John11

I would start with writing two equations.

1. how much Ca₃(AsO₄)₂ I will get from 98,49 g of Sb₂AsS₂ + how much Ca₃(AsO₄)₂ I will get from 98,49 g of As₂S₃.

2. mixture cointains only Sb₂AsS₂ and As₂S₃ (they give 100 % in all).