The masses can be found by substractions:
- Mass of CaSO₄.H2O (hydrate):
16.05 g - 13.56 g = 2.49 g
15.07 g - 13.56 g = 1.51 g
- The mass of water is equal to the difference between the mass of the hydrate and the mass of the anhydrate:
2.49 g - 1.51 g = 0.98 g
- The percent of water is found by the formula:
massWater ÷ massHydrate * 100%
0.98 g ÷ 2.49 g * 100% = 39.36%
- The mole of water is calculated using water's molecular weight (18g/mol):
0.98 g ÷ 18 g/mol = 0.054 mol water
- A similar procedure is made for the mole of salt (CaSO₄ = 136.14 g/mol)
1.51 g ÷ 136.14 g/mol = 0.011 mol CaSO₄
- The ratio of mole of water to mole of anhydrate is:
0.054 mol water / 0.011 mol CaSO₄ = 0.49
In other words the molecular formula for the hydrate salt is CaSO₄·0.5H₂O
The correct answer is a. This is because the pH of a solution is defined as -log10(concentration of H+ ions). An inverse logarithmic scale such as this means that a solution with a lower concentration of H+ ions will have a higher pH than one with a higher concentration. Therefore we know that the pH of the second sample will be higher than the first.
Since the logarithmic scale has the base 10, a change by 1 on the scale is a consequence of multiplication/division of the H+ concentration by a factor of 10. As the scale is inverse, this means that a decrease of concentration by factor 1000 is equivalent to increasing the pH by (1000/10) = 3.
<span>A </span>chemical formula<span> is a way of expressing information about the proportions of </span>atoms<span> that constitute a particular</span>chemical compound<span>, using a single line of </span>chemical element<span> symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and </span>plus<span> (+) and </span>minus<span> (−) signs. A chemical formula is not a </span>chemical name showing how the atoms are arranged.
The concentration of the HCl solution is 0.72 M.
<h3>How do we calculate the concentration?</h3>
Concentration of the required solution by the use of the known concentration solution will be determine by using the below equation as:
M₁V₁ = M₂V₂, where
- M₁ & V₁ are the molarity and volume of the HCl solution.
- M₂ & V₂ are the molarity and volume of the NaOH solution.
On putting values in the above equation, we get
M₁ = (1)(0.018) / (0.025) = 0.72 M
Hence required concentration of HCl is 0.72M.
To know kore about molarity, visit the below link:
brainly.com/question/24305514
#SPJ1
