A 50. 0-g sample of liquid water at 25. 0 °c is mixed with 23. 0 g of water at 79. 0 °c. The final temperature of the water is _
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Taking into account the definition of molarity, 14.028 grams of sodium chloride must be added to make 400 mL of a 0.600 M sodium chloride.
<h3>Definition of molarity</h3>Molar concentration or molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.
The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:
Molarity is expressed in units .
In this case, you know:
- Molarity= 0.600 M
- number of moles= ?
- volume= 400 mL= 0.400 L (being 1000 mL= 1 L)
Replacing in the definition of molarity:
Solving:
number of moles= 0.600 M× 0.400 L
number of moles= 0.24 moles
<h3>Mass of sodium chloride</h3>Being the molar mass of sodium chloride 58.45 , that is the amount of mass that a substance contains in one mole, the mass of sodium chloride can be calculated as:
0.24 moles×58.45 = 14.028 grams
Finally, 14.028 grams of sodium chloride must be added to make 400 mL of a 0.600 M sodium chloride.
Learn more about molarity:
Using the z-distribution, it is found that the smallest sample size required to obtain the desired margin of error is of 4330.
<h3>What is a confidence interval of proportions?</h3>A confidence interval of proportions is given by:
In which:
is the sample proportion.
- z is the critical value.
- n is the sample size.
The margin of error is given by:
In this problem:
- The estimate of the proportion is of
.
- The desired margin of error is of M = 0.01.
- 90% confidence level, hence
, z is the value of Z that has a p-value of
, so
.
Then, we solve for n to find the minimum sample size.
Rounding up, the smallest sample size required to obtain the desired margin of error is of 4330.
To learn more about the z-distribution, you can take a look at brainly.com/question/12517818