An unknown metal (M) was found not to react with either water or ...

Question

An unknown metal (M) was found not to react with either water or steam, but its reactivity with aqueous acid was not investigated. When a 1.000 g sample of the metal was burned in oxygen and the resulting metal oxide converted to a metal sulfide, 1.504 g of sulfide was obtained. What is the identity of the metal?

Accepted Answer

Welcome back everyone. The reactivity of a metal M was studied and it was recorded that it does not react with water or steam but can displace protons from acids to produce hydrogen gas. A mass of five or 1.500 g of the metal was reacted with oxygen to produce a metal oxide. And then the metal oxide was further reacted to form a metal sulfide. If 1.905g of the metal sulfide was produced, determined the identity of the metal. We want to recall our activity series table in our textbooks. And specifically, we want to recall this series of metals that displace hydrogen from assets. So we would recall the medal specifically beginning with cadmium since its highest up in our activity series which is corresponding to the cadmium two plus canyon below cadmium. On our activity series, we have our metal Cobalt which forms the cobalt two plus caddy. On below Cobalt, we have nickel forming the nickel to plus catalon and 10, we have which forms the S N two plus caddy on and then we have led which is the most bottom of our activity series forming the lead two plus catalon. And so all of these metals can displace hydrogen from acids. Now, because we need to determine the identity of our metal. We're going to make a general formula for our metal sulfide represented as M S. So we need to focus on first using the info from the pumped finding our mass of R S being our sulfide. So for the mass of our sulfide S, We would begin with taking the amount of the metal sulfide produced given in the prompt as 1.905g subtracted from the mass of the metal mentioned in the prompt as 1.500 g. And so this difference gives us our mass of our sulfide equal 2.405g. Now, with this mass of our sulfide in our metal sulfide, we want to find moles of our sulfide. And so beginning with our mass 0.405 g, we're going to multiply by the molar mass of sulfur in which on our product tables, we see is equivalent to 32.66 g of sulfur equivalent to one mole of sulfur. So canceling out grams, we're left with moles and this is going to result in a in our moles of our sulfide equal to 0. moles of our sulfide. And now that we have most of our sulfide, we can use it in a ratio to find moles of our metal. And so beginning with our moles of sulfide, 0.1263 moles of our sulfide. We're going to multiply by the molar ratio To go from moles of our sulfide, two moles of our metal. And in our, in our chemical formula for our metal sulfide, we should have a 1-1 ratio. So one mole of our sulfide for one mole of our metal using this ratio and calculating things into our calculator. We find that our, most of our metal are 0.1263 moles of our metal. And now we need to find the mass so that we can identify its identity. So we want to recall that for the molar mass of our mettle, we would take crams over moles. And so we know that our mass of our metal according to the prompt is 1.500 g. And our moles, we just calculated to be 0. moles. And so we have grams per mole in which we will have our molar mass equal to a value of 118. g. Sorry, this should be grams per mole. Now, with the smaller mass, we want to refer to our periodic table. So on our periodic table, we would see that this smaller mass corresponds to the mass of tin in which we have a mass of about 118.71 g per mole. And so we would therefore have identified our identity, our identity of the metal being tin. And so what's highlighted in yellow and actually, we shouldn't highlight the mass, but what's highlighted in yellow for the name of our metal being tin would be our final answer to complete this example corresponding to choice c in the multiple choice. I hope that everything I went through was clear. If you have any questions, please leave them down below and I'll see everyone in the next video.

Watch next