We need to first find the molarity of Ba(OH₂) solution.
A mass of 3.24 mg is dissolved in 1 L solution.
Ba(OH)₂ moles dissolved - 3.24 x 10⁻³ g/171.3 g/mol = 1.90 x 10⁻⁵ mol
dissociaton of Ba(OH)₂ is as follows;
Ba(OH)₂ --> Ba²⁺ + 2OH⁻
1 mol of Ba(OH)₂ dissociates to form 2OH⁻ ions.
Therefore [OH⁻] = (1.90 x 10⁻⁵)x2 = 3.8 x 10⁻⁵ M
pOH = -log[OH⁻]
pOH = -log (3.8 x 10⁻⁵)
pOH = 4.42
pH + pOH = 14
therefore pH = 14 - 4.42
pH = 9.58
The significant figures will be 1.
As, weight of acetylsalicylic acid = 0. 4 g
We obtain 400 mg when we convert 0.4g of acetylsalicylic acid to mg.
So, 400 milligrams are worth 0.4 grams when converted to grams.
There is just one significant figure because 0 before a decimal is not significant i.e. 4.
<h3><u>What are significant figures?</u></h3>
The digits of a number that have relevance in relation to the measurement's resolution are known as significant figures. Additionally known as significant figures in chemistry. All experimental measurements are subject to some degree of uncertainity.
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Check more such questions based on significant figure here:
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The amount ( in moles of excess reactant that is left is 0.206 moles
Explanation
FeS(s) + 2HCl (aq) → FeCl2 (s) + H2S (g)
- by use of mole ratio of FeS: HCl which is 1:2 this means that 0.223 mole of FeS reacted completely with 0.223 x 2/1 =0.446 moles 0f FeCl2.
- HCl was in excess because 0.446 moles of HCl reacted and initially there was 0.652 moles.
- Therefore the amount that was left
= 0.652- 0.446 =0.206 moles
Explanation:
It is known that the value of Avogadro's number is 
.
Therefore, calculate moles of gold atoms as follows.
Moles of gold atom = 
= 
= 
mol
= 1.99 mol
Thus, we can conclude that 1.99 mol of gold atoms are equivalent to 
atoms.
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