A sample of silicon has an average atomic mass of 28.084amu. In the sample, there are three isotopic forms of silicon. About 92.22% of silicon atoms are 27.9769amu, which have the mass of 28Si; about 4.68% are 28.9764amu, which have the mass of 29Si, and the isotope 30Si, makes up the remaining 3.10%. Calculate the atomic mass of 30Si. Report your answer with three significant figures <u>The percentage abundance for </u><u>isotope </u><u>is 3.09 %.</u>
<h3>What is isotopes?</h3>
Isotopes are two or more atom types that share the same atomic number (number of protons in their nuclei), location in the periodic table, and chemical element but have distinct nucleon numbers (mass numbers) as a result of having a different number of neutrons in their nuclei. Although the chemical properties of each isotope of a given element are nearly identical, they differ in their atomic weights and physical characteristics.
The word "isotope" is derived from the Greek words "isos" and "topos," both of which imply "the same location." As a result, the name refers to the fact that various isotopes of a given element occupy the same spot on the periodic table. Scottish physician and author Margaret Todd first used it in a recommendation in 1913.
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HCl:
<span>
m=48,2g
M=36,5g/mol
n = m/M = 48,2g / 36,5g/mol = 1,32mol
1mol : 4mol
MnO</span>₂ + 4HCl ⇒ MnCl₂ + Cl₂ + 2H₂O
0,86mol : 1,32mol
limiting reagent
0,33 will react
HCl is limiting reagent.
<h3>Answer
</h3>
Option C= ions are exchanged between two compounds.
<h3>Explanation
</h3>
A double displacement reaction, also known as a double replacement reaction or metathesis, is a type of chemical reaction where two compounds react, and the positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products. For example,
Na2S + 2HCl → H2S + 2NaCl
Option D is incorrect because electrons are exchanged between the atoms in oxidation –reduction reactions.
C. Positive acceleration describes an increase in speed; negative acceleration describes a decrease in speed. ( I put A & it was not the correct answer, the answer was C )
1. At constant tempaerature and pressure, 3 tablets produce 600cm^3 of gas
Thus calculating for 1 tablet that produces 600 / 3 = 200 cm^3
So now two tablets produce 200 x 2 = 400 cm^3
2. We have the equation PV = nRT, n being the number of moles
Pressure P = 1,000 kPa
Volume V = 3 L
R = 8.31 L kPa/mol-K
Temperature T = 298 K
n = PV / RT = (1000 x 3) / (8.31 x 298) = 3000 / 2476.38 = 1.21 moles
Number of moles = 1.21 moles.
