Answer:
2.8
Explanation:
First, we will calculate the molarity of the acetylsalicylic acid solution.
M = mass of solute (g) / molar mass of solute × volume of solution (L)
M = 0.327 g / 180.158 g/mol × 0.237 L
M = 7.66 × 10⁻³ M
For a weak acid such as acetylsalicylic acid, we can find the concentration of H⁺ using the following expression.
[H⁺] = √(Ca × Ka)
where,
Ca: concentration of the acid
Ka: acid dissociation constant
[H⁺] = √(7.66 × 10⁻³ × 3.3 × 10⁻⁴)
[H⁺] = 1.6 × 10⁻³ M
The pH is:
pH = -log [H⁺]
pH = -log 1.6 × 10⁻³ = 2.8
Answer:
E = 5.69x10⁻²⁸m
Explanation:
To solve this question we neeed to convert the wavelength in meters to energy in joules using the equation:
E = hc / λ
<em>Where E is energy in joules, h is Planck's constant = 6.626x10⁻³⁴Js</em>
<em>c is light constant = 3.0x10⁸m/s</em>
<em>And λ is wavelength in meters = 349m</em>
Replacing:
E = 6.626x10⁻³⁴Js*3.0x10⁸m/s / 349m
E = 5.69x10⁻²⁸m
The balanced chemical reaction for this would be written as:
2Mg + O2 = 2MgO
We use this reaction and the amount of the reactant given to calculate for the amount of magnesium oxide that is produced. We do as follows:
1.5 g Mg (1 mol / 24.31 g) ( 2 mol MgO / 2 mol Mg ) (40.30 g /1 mol ) = 2.49 g MgO produced
