Sure, let's address the two questions one by one.
Q1: What piece of equipment does Joshua need to measure the amount of salt in the 200 mL of sea water?
Answer:
To measure the amount of salt in 200 mL of sea water, Joshua would typically require the following pieces of equipment:
1. Analytical Balance: This is used to accurately measure the mass of substances. It is vital for measuring the weight of the salt after it has been separated from the water.
2. Graduated Cylinder or Volumetric Flask: These are used to measure the accurate volume of sea water. In this case, Joshua would need a graduated cylinder or volumetric flask to measure out exactly 200 mL of sea water.
3. Evaporation Dish: An evaporation dish allows the water to evaporate, leaving behind the salt. The dish should be made of a material that does not react with the sea water or the salt.
4. Heat Source: This can be a hotplate or Bunsen burner to evaporate the water from the sea water, leaving the salt behind in the evaporation dish.
5. Desiccator: This is used to cool the evaporation dish and its contents in a dry environment, preventing moisture from the air from re-dissolving the salt.
In summary, Joshua needs an analytical balance, graduated cylinder or volumetric flask, evaporation dish, heat source, and a desiccator to measure the amount of salt in 200 mL of sea water.
Q2: Joshua's three readings for the mass of salt after evaporation are 6.5 g and 7.5 g. What value for the weight/ mass of salt should be used?
Answer:
To determine the single value for the mass of salt based on Joshua's readings, we can compute the average (mean) of the provided readings. This involves taking the sum of the readings and dividing by the number of readings.
Given readings:
- 6.5 g
- 7.5 g
Steps to calculate the average:
1. Sum of the readings: [tex]\( 6.5 \, g + 7.5 \, g = 14 \, g \)[/tex]
2. Number of readings: 2
3. Average (mean) mass of salt: [tex]\(\frac{14 \, g}{2} = 7 \, g\)[/tex]
Therefore, the value for the mass of salt that Joshua should use is 7.0 grams.
