In a laboratory experiment, a 10.0-mL sample of NaCl solution is poured into an evaporating dish with a mass of 24.10 g. The combined mass of the evaporating dish and NaCl solution is 36.15 g. After heating, the evaporating dish and dry NaCl have a combined mass of 25.50 g.
a. What is the mass percent (m/m) of the NaCl solution?

Question

In a laboratory experiment, a 10.0-mL sample of NaCl solution is poured into an evaporating dish with a mass of 24.10 g. The combined mass of the evaporating dish and NaCl solution is 36.15 g. After heating, the evaporating dish and dry NaCl have a combined mass of 25.50 g.
a. What is the mass percent (m/m) of the NaCl solution?

a. What is the mass percent (m/m) of the NaCl solution?

Accepted Answer

Welcome back everyone. An evaporating dish with a mass of 42.6 g was used to hold a 20 mL iron two sulfate solution. The mass of the evaporating dish with the solution is 68.5 g. The solution was heated to remove all the water and the final mass of the evaporating dish. And the dry iron two sulfate was 48.5 g. Calculate the mass percent of the original iron two sulfate solution. Let's recall that mass percent is defined as our mass of our solute, which is our substance being dissolved in grams divided by our mass of our solution in grams. This quotient is then multiplied by 100%. We're going to need to begin by calculating our mass of our solution in which we would take our mass of our evaporating dish plus our solution. And we want to subtract our mass of our evaporating dish individually. So plugging in our nodes are mass of our evaporating dish. Plus our solution was given from the prompt as 68.5 g which is subtracted from our mass of our evaporating dish of 42.6 g which was also given. And from this difference, we'd find our mass of our solution equal to 25.9 g. Now we're going to need our mass of our solute, which is our substance being dissolved. In this case, iron two sulfate F E S 04. Now, we need to consider iron two sulfate in its dried form, which is going to be an hydros iron two sulfate. So to calculate this, we would take our mass of our evaporating dish plus our anhydrous iron two sulfate subtracted from our mass of our evaporating dish. So plugging in our nodes, our mass of our evaporating dish and our dried iron tree sulfate is given from our prompt as 48.5 g, which is then, I'm sorry, this says grams and this is subtracted from our mass, our evaporating dish which was given from our prompt as 42. g. And from this difference, we'll find our mass of our and hydrous iron two sulfate equal to 5.9 g. Now, let's get into calculating our percent mass of our iron two sulfate solution in which we would plug in our mass of our dried iron two sulfate, which we determined was 5.9 g, which is divided by our mass of our solution, which we determined above as 25.9 g. We then want to place this in parentheses and multiply by 100. So in our next line we'd have a mass percent equal to about 23. I'm sorry, this says equal to about 23%. And so 23% would be our final answer as our mass percent of our original solution. I hope that this made sense and let us know if you have any questions.

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Key Concepts

Mass Percent (m/m)

Mass of Solute and Solution

Evaporation and Drying