The formula units in the substances are as follows:
- Br2 = 8.99 × 10^23 formula units
- MgCl2 = 1.51 × 10^24 formula units
- H2O = 2.57 × 10^24 formula units
- Fe = 2.57 × 10^24 formula units
<h3>How many moles are in 239.2 g of the given substances?</h3>
The moles of the substances are determined from their molar mass.
Molar mass of the substances is given as follows:
- Br2 = 160 g/mol
- MgCl2 = 95 g/mol
- H2O = 18 g/mol
- Fe = 56 g/mol
Formula units = mass/molar mass × 6.02 × 10^23
The formula units in the substances are as follows:
- Br2 = 239.2/160 × 6.02 × 10^23 = 8.99 × 10^23 formula units
- MgCl2 = 239.2/95 × 6.02 × 10^23 = 1.51 × 10^24 formula units
- H2O = 239.2/18 × 6.02 × 10^23 = 2.57 × 10^24 formula units
- Fe = 239.2/56 × 6.02 × 10^23 = 2.57 × 10^24 formula units
In conclusion, the number of formula units is derived from the moles and Avogadro number.
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Answer:
Polarity in chemistry referred to physical properties of compounds related to solubility, melting and boiling properties.
Polarity of black pepper can be seen when black pepper is sprinkled on water. The balck pepper float on water and get displaced if touched.
It means black pepper is non-polar and have no difference in electronegativity between bonded atoms. Black pepper is so light in weight and non-polar, the surface tension of water keep it floating in the water.
Data: molar mass 470 g/mol
Percent composition:
Hg = 85.0%
Cl = 15.0%
Solution:
1) Convert % to molar ratios
A. Base: 100 g
=> Hg = 85.0 g / 200.59 g/mol = 0.4235 mol
Cl = 15.0 g / 35.45 g/mol = 0.4231 mol
B. divide by the higher number and round to whole number
Hg = 0.4325 / 0.4231 = 1.00
Cl = 0.4231 / 0.4231 = 1.00
=> Empirical formula = Hg Cl
2) Find the mass of the empirical formula:
HgCl: 200.59 g/mol + 35.45 g/mol = 236.04
3) Determine how many times is the empirical mass contained in the molecular mass:
470 g/mol / 236.04 = 1.99 ≈ 2
=> Molecular formula = Hg2 Cl2.
Answers:
Empirical formula HgCl
Molecular Formula Hg2Cl2
Answer:
a) a0 was 46.2 grams
b) It will take 259 years
c) The fossil is 1845 years old
Explanation:
<em>An unknown radioactive substance has a half-life of 3.20hours . If 46.2g of the substance is currently present, what mass A0 was present 8.00 hours ago?</em>
A = A0 * (1/2)^(t/h)
⇒ with A = the final amount = 46.2 grams
⇒ A0 = the original amount
⇒ t = time = 8 hours
⇒ h = half-life time = 3.2 hours
46.2 = Ao*(1/2)^(8/3.2)
Ao = 261.35 grams
<em>Americium-241 is used in some smoke detectors. It is an alpha emitter with a half-life of 432 years. How long will it take in years for 34.0% of an Am-241 sample to decay?</em>
t = (ln(0.66))-0.693) * 432 = 259 years
It will take 259 years
<em>A fossil was analyzed and determined to have a carbon-14 level that is 80% that of living organisms. The half-life of C-14 is 5730 years. How old is the fossil?</em>
<em />
t = (ln(0.80))-0.693) * 5730 = 1845
The fossil is 1845 years old
The best option is a. but it is not complete!
Both liquids have different densities, it's true. But they are immiscible liquids and they don't form a solution.
