Answer:
Empirical formula (which matches the molecular formula) is = PbC₈H₂₀
Explanation:
Our sample: 60 g of tetraethyl lead
In order to determine the compound empirical formula we need the centesimal composition:
(Mass of element / Total mass) . 100 =
(38.43 g lead / 60g ) . 100 = 64.05%
(17.83 g C / 60g) . 100 = 29.72%
(3.74 g H / 60g) . 100 = 6.23 %
These % are the mass of the elements in 100 g of compound. Let's find out the moles of them:
64.05 g / 207.2 g/mol = 0.309 moles
29.72 g / 12 g/mol = 2.48 moles
6.23 g/ 1 g/mol = 6.23 moles
Next, we divide the moles, by the lowest value of them (0.309)
0.309 / 0.309 = 1 mol Pb
2.48 / 0.309 = 8 mol C
6.23 / 0.309 = 20 mol H
There, we have our formula PbC₈H₂₀
Pressure varies in the atmosphere because air molecules are being pulled down towards the center of the earth-hope this helps!
A compound<span> is a </span>molecule<span> that contains at least two different elements. </span>All compounds<span> are </span>molecules<span> but not </span>all molecules<span> are </span>compounds<span>. </span>Molecularhydrogen (H2<span>), </span>molecular<span> oxygen (O</span>2<span>) and </span>molecular<span> nitrogen (N</span>2) are notcompounds<span> because each is composed of a single element.</span>
These are two questions and two answers
Question 1.
Answer:
Explanation:
<u>1) Data:</u>
a) m = 9.11 × 10⁻³¹ kg
b) λ = 3.31 × 10⁻¹⁰ m
c) c = 3.00 10⁸ m/s
d) s = ?
<u>2) Formula:</u>
The wavelength (λ), the speed (s), and the mass (m) of the particles are reltated by the Einstein-Planck's equation:
- h is Planck's constant: h= 6.626×10⁻³⁴J.s
<u>3) Solution:</u>
Solve for s:
Substitute:
- s = 6.626×10⁻³⁴J.s / ( 9.11 × 10⁻³¹ kg × 3.31 × 10⁻¹⁰ m) = 2.20 × 10 ⁶ m/s
To express the speed relative to the speed of light, divide by c = 3.00 10⁸ m/s
- s = 2.20 × 10 ⁶ m/s / 3.00 10⁸ m/s = 7.33 × 10 ⁻³
Answer: s = 7.33 × 10 ⁻³ c
Question 2.
Answer:
Explanation:
<u>1) Data:</u>
a) m = 45.9 g (0.0459 kg)
b) s = 70.0 m/s
b) λ = ?
<u>2) Formula:</u>
Macroscopic matter follows the same Einstein-Planck's equation, but the wavelength is so small that cannot be detected:
- h is Planck's constant: h= 6.626×10⁻³⁴J.s
<u>3) Solution:</u>
Substitute:
- λ = 6.626×10⁻³⁴J.s / ( 0.0459 kg × 70.0 m/s) = 2.06 × 10 ⁻³⁴ m
As you see, that is tiny number and explains why the wave nature of the golf ball is undetectable.
Answer: 2.06 × 10 ⁻³⁴ m.
