A student used 10 mL water instead of 30 mL for extraction of salt from mixture. How may this change the percentage of NaCl extracted?
My book says:
% NaCl= (grams of NaCl / total grams of mixture) x 100
What I don't get is if it does change the percentage, why? It says the percentage depends on grams but the question is dealing with mL which is volume. Can someone please help me understand?
both materials have mass associated with the volume. By changing the volume of water, you also change the mass involved.
The percentage of NaCl extracted can be affected by the change in the volume of water used for extraction, even though the percentage is typically calculated using grams.
In the given equation:
% NaCl = (grams of NaCl / total grams of mixture) x 100
The grams of NaCl is typically determined by the mass of the NaCl in the mixture, while the total grams of the mixture can be determined by the mass of the entire mixture.
However, since the question provided the volumes of water used instead of masses, we need to consider the relationship between volume and mass.
Assuming the density of water is close to 1 g/mL, we can conclude that 10 mL of water is equivalent to approximately 10 grams of water. Similarly, 30 mL of water will be approximately 30 grams.
If the amount of water used for extraction is decreased from 30 mL to 10 mL, the total mass of the mixture (water + NaCl) will decrease by 20 grams.
In calculating the percentage of NaCl, the decreased total mass will result in a higher percentage. This is because the grams of NaCl stay the same, but the total grams of the mixture decrease.
To summarize, the change in the volume of water used for extraction affects the mass of the mixture, which in turn affects the calculated percentage of NaCl extracted.
To understand why the change in the volume of water used for extraction can affect the percentage of NaCl extracted, we need to consider the concept of concentration. Concentration refers to the amount of a substance present in a given volume or mass.
In this case, when we say "grams of NaCl," we are referring to the mass of NaCl. The units of grams and milliliters (mL) represent different properties - grams measure mass, while mL measure volume. However, in the context of this question, we can assume that the density of water is approximately 1 g/mL. This means that 1 mL of water has a mass of 1 gram.
Now, let's consider the example scenario:
- Initially, 30 mL of water is used for extraction.
- The resulting mixture after extraction is analyzed to determine the percentage of NaCl extracted.
Using the formula provided in your book:
% NaCl = (grams of NaCl / total grams of mixture) x 100
With the initial volume of 30 mL, you would have used:
- 30 mL of water, which corresponds to 30 grams of water
- A certain amount of NaCl (let's say x grams) from the mixture
Therefore, the total grams of the mixture would be: 30 grams (water) + x grams (NaCl).
If you substitute these values into the formula, you can calculate the percentage of NaCl extracted using 30 mL of water.
Now, consider the scenario where only 10 mL of water is used for extraction:
- In this case, you would have used 10 grams of water (since 1 mL of water is approximately 1 gram).
- The amount of NaCl extracted (x grams) remains the same.
So, the total grams of the mixture would be: 10 grams (water) + x grams (NaCl).
When you substitute these values into the formula, you can calculate the percentage of NaCl extracted using 10 mL of water.
Comparing the two percentages obtained from the calculations, you will likely find they are different. This difference arises because the total grams of the mixture used to calculate the percentage changes based on the volume of water used for extraction.
In summary, changing the volume of water used for extraction affects the total grams of the mixture, which, in turn, affects the calculated percentage of NaCl extracted.