Answer:
Explanation:
Ca(In)²⁺ + EDTA → Ca(EDTA)²⁺ + In
We use the volume of EDTA consumed in the titration to <u>calculate the moles of Ca⁺² ions</u>:
- 0.012 L * 0.0600 M *
= 7.20x10⁻⁴ mol Ca⁺²
Now we <u>calculate the molarity</u>:
- 7.20x10⁻⁴ mol Ca⁺² / 0.050 L = 0.0144 M
To calculate in ppm, we <u>use the moles of Ca⁺² and convert to mg of CaCO₃:</u>
- 7.20x10⁻⁴ mol Ca⁺² = 7.20x10⁻⁴ mol CaCO₃
- 7.20x10⁻⁴ mol CaCO₃ * 100g/mol *
= 72 mg CaCO₃
Finally, <u>the concentration in ppm</u> is:
- 72 mg CaCO₃ / 0.050L = 1440 ppm
Calculate first the number of moles of ethylene glycol by dividing the mass by the molar mass.
n = (6.21 g ethylene glycol) / 62.1 g/mol
n = 0.1 mol
Then, calculate the molality by dividing the number of moles by the mass of water (in kg).
m = 0.1 mol/ (0.025 kg) = 4m
Then, use the equation,
Tb,f = Tb,i + (kb)(m)
Substituting the known values,
Tb,f = 100°C + (0.512°C.kg/mol)(4 mol/kg)
<em>Tb,f = 102.048°C</em>
Answer:
3.925 mol.
Explanation:
- From the balanced equation:
<em>2 Na₂O₂(s) + 2 H₂O(l) → 4 NaOH(s) + O₂(g)
,</em>
It is clear that 2 moles of Na₂O₂ react with 2 moles of H₂O to produce 4 moles of NaOH and 1 mole of O₂
.
<em>Using cross multiplication:</em>
4 moles of NaOH produced with → 1 mole of O₂
.
15.7 moles of NaOH produced with → ??? mole of O₂
.
<em>∴ The no. of moles of O₂ made =</em> (1 mole)(15.7 mole)/(4 mole) = <em>3.925 mol.</em>
Radioactivity in our world <span>b. is as old as the universe.
</span><span>Radioactive atom spontaneously emits energetic particles or waves, while decays on lighter nuclei (atoms with smaller atomic mass). Radioactivity is used to calculate how old is Earth and living things, for that purpose isotope of carbon is used.</span>