Answer:
a) 5.40 g B : [tex]3.012\times 10^{23}[/tex] atoms
b) 0.250 mol K : [tex]1.51\times 10^{23}[/tex] atoms
c) 0.0384 mol K : [tex]0.23\times 10^{23}[/tex] atoms
d) 0.02550 g Pt: [tex]7.8\times 10^{19}[/tex] atoms
e) [tex]1.00\times 10^-{10} g[/tex] Au: [tex]0.03\times 10^{13}[/tex] atoms
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.
To calculate the moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}[/tex]
a) 5.40 g B
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{5.40g}{11g/mol}=0.5moles[/tex]
1 mole of boron contains = [tex]6.023\times 10^{23}[/tex] atoms
Thus 0.5 moles of boron contain =[tex]\frac{6.023\times 10^{23}}{1}\times 0.5=3.012\times 10^{23}[/tex] atoms
b) 0.250 mol K
1 mole of potassium (K) contains = [tex]6.023\times 10^{23}[/tex] atoms
Thus 0.250 moles of potassium contain =[tex]\frac{6.023\times 10^{23}}{1}\times 0.250=1.51\times 10^{23}[/tex] atoms
c) 0.0384 mol K
1 mole of potassium (K) contains = [tex]6.023\times 10^{23}[/tex] atoms
Thus 0.0384 moles of potassium (K) contain =[tex]\frac{6.023\times 10^{23}}{1}\times 0.0384=0.23\times 10^{23}[/tex] atoms
d) 0.02550 g Pt
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{0.02550 g}{195g/mol}=1.3\times 10^{-4}moles[/tex]
1 mole of platinum contains = [tex]6.023\times 10^{23}[/tex] atoms
Thus [tex]1.3\times 10^{-4}moles[/tex] of platinum contain=[tex]\frac{6.023\times 10^{23}}{1}\times 1.3\times 10^{-4}=7.8\times 10^{19}[/tex] atoms
e) [tex]1.00\times 10^-{10}g[/tex] Au,
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{1.00\times 10^{-10}g}{197g/mol}=0.005\times 10^{-10}moles[/tex]
1 mole of gold contains = [tex]6.023\times 10^{23}[/tex] atoms
Thus [tex]0.005\times 10^{-10}moles[/tex] of platinum contain=[tex]\frac{6.023\times 10^{23}}{1}\times 0.005\times 10^{-10}=0.03\times 10^{13}[/tex] atoms
Which of the following are changing when a change of state is occurring?
Select all that apply.
temperature change
amount of intermolecular bonds
vibration of particles
position of particles
Mandy is testing an unknown solution to determine whether it is an acid or a base. she places a piece of red litmus paper into the solution and the paper turns blue. mandy's unknown solution
A substance is 35.7% carbon by mass. how much carbon could be recovered from 769 g of the substance?
The amount of carbon that could be recovered from 769g of a substance that is 35.7% carbon by mass is approximately 275g.
Explanation:The question involves a percentage by mass calculation, which falls under the subject of Chemistry. The substance in question is 35.7% carbon by mass. Therefore, to find the amount of carbon in a 769g sample, we multiply the total mass of the substance by the percentage of carbon.
Here's the calculation: 769g (total mass) x 0.357 (percentage of carbon as a decimal) = 274.653g. Therefore, we can recover approximately 275g (if we round to the nearest whole number) of carbon from the 769 g of the substance.
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To find how much carbon is in 769 g of a substance that is 35.7% carbon by mass, multiply 769 g by 0.357. This calculation shows that 274.833 g of carbon can be recovered.
To determine this, we can use the percentage by mass to find the amount of carbon in the total mass of the substance. Here's the step-by-step calculation:
First, convert the percentage into a decimal: 35.7% = 0.357
Amount of carbon = mass of the substance × percentage of carbon (in decimal form)
Amount of carbon = 769g × 0.357
Amount of carbon = 274.553g
Therefore, you could recover approximately 274.553 grams of carbon from 769 grams of the substance.
1.) If a neutral atom of chlorine has 17 electrons and 18 neutrons, how many electrons are in the second energy shell of this atom?
2.) If a neutral atom of chlorine has 17 electrons and 18 neutrons, how many electrons are in the outermost, or valence, shell of this atom?
Answer: 1. 8 electrons
2. 7 electrons
Explanation: energy shell are orbits which Carry's electrons around an atom's nucleus.
To determine the number of electrons in an energy shell, use the formula
2(n^2)
n= number of energy shell
Therefore the second energy shell is n=2
Substituting n in the equation above,
2(2^2)=8
2. Valence electrons are the electrons on the outermost shell of an atomic nucleus.
The group number of an element is the same as the valence electrons of that element.
Therefore chlorine which belongs to group 7 elements has 7 valence electron.
We can also get the valence electrons using the K L M N shell.
The K shell which has maximum of 2 electrons, while other shells can contain maximum of 8 electron.
SEE PICTURE ATTACHED TO UNDERSTAND THE K L M N SHELL BETTER.
How much energy is released if 3705g of octane are burned
I really need some help and explaining with the Heat of Combustion Lab.
1. You may recall that the products of the complete combustion of a hydrocarbon are water vapor and carbon dioxide gas. Write the balanced equation showing the combustion of methane. Do not forget to include the states of matter of the reactants and the products. Hint: Methane is a gas at standard temperature and pressure.
what are the five indicators of a chemical change
Write the net ionic equation for the precipitation of cobalt(ii) carbonate from aqueous solution
HELP ASAP!!!
Carbon dioxide (CO2) is a gaseous compound. Calculate the percent composition of this compound. Answer using three significant figures.
What is the percent by mass of carbon?
%
What is the percent by mass of oxygen?
%
What is the length of the hypotenuse of the right triangle ABC in the figure?
A. 6.2
B. 11.0
C. 5.8
D. 7.2
The chart seen here shows the decay of a sample of carbon-14 over a period of 33,000 years. What is the approximate half-life of carbon 14?
5,500 ears if u using usatestprep
Which of these is an example of a physical change?
sugar, when heated, producing carbon dioxide and water
solid ice, when heated, turning into liquid water
sodium, when exposed to chlorine, forming sodium chloride
aluminum, when heated in air, forming aluminum oxide
Answer: Option (b) is the correct answer.
Explanation:
When there is no change in chemical composition of a substance then this change is known as physical change.
Where as when there is change in chemical composition of a substance then it is known as chemical change.
When sugar is heated, it results in the formation of carbon dioxide and water. This means that composition of sugar has changed thus, it is a chemical change.
When solid ice is melted, it turns into liquid. This shows that only state of water has changed. There is no change in chemical composition because when we freeze water then again liquid water changes into solid ice. Thus, it is a physical change.
When sodium reacts with chlorine then the reaction is as follows.
[tex]2Na + Cl_{2} \rightarrow 2NaCl[/tex]
It shows that chemical composition of sodium has changed due to the formation of sodium chloride. Thus, it is a chemical change.
Also, when aluminium is is heated in air then it results in the formation of aluminium oxide. This means that the chemical composition of aluminium has changed.
Hence, we can conclude that out of the given options, solid ice, when heated, turning into liquid water is an example of a physical change.
Please help!!!!! Why is a spectrum for a given element unique for that element? A. No element has more than two electrons in the first shell. B. Each element has a unique arrangement of electrons. C. Atoms of different elements have different masses. D. Atomic nuclei contain no electrons.
Each element has a unique arrangement of electrons, so each element has different spectrum. Therefore, the correct option is option B.
What is element?The quantity of protons an element has defines it. An element's atoms all contain the same amount of protons, but its electron and neutron counts might vary. Ions are produced by altering the electron to proton ratio, whereas isotopes are produced by altering the neutron count.
A material that cannot be destroyed chemically is referred to as a chemical element. Although chemical processes cannot modify an atom, nuclear reactions can create new elements. Each element has a unique arrangement of electrons, so each element has different spectrum.
Therefore, the correct option is option B.
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Sheena wants to list the outer planets from smallest to largest. Which is correct? Jupiter, Saturn, Uranus, Neptune Neptune, Jupiter, Uranus, Saturn Neptune, Uranus, Saturn, Jupiter Saturn, Uranus, Neptune, Jupiter
When the concentration of solute in a solid solution exceeds its solubility limit, a new solid solution or phase forms that has a composition distinctly different than the original solid solution?
When solute concentration exceeds the solubility limit in a solution, a supersaturated solution is created, which subsequently initiates precipitation in order to achieve equilibrium. This results in the formation of a new solid phase that is distinct from the original solution.
Explanation:The concept you're referring to involves solubility and the formation of new phases when the concentration of a solute in a solution exceeds its solubility limit. Solubility refers to the maximum amount of solute that can be dissolved in a solvent at a given temperature. When this limit is surpassed, a supersaturated solution is formed. This is not a stable state, and it often results in precipitation. This is the process where a solute becomes insoluble and forms a new, separate solid phase.
For instance, if we take a saturated solution of silver chloride (AgCl), and add more AgCl to it, the excess will precipitate out of solution. Here, the concentration of AgCl has exceeded its solubility, leading to the formation of a new solid phase that is distinct from the original solution.
The exact composition and form of the new solid phase can depend on a variety of factors, including the type of solvent and solute involved, temperature, and pressure.
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______ tend to lose electrons in chemical reactions, forming positive ions. nonmetals tend to _____ electrons in chemical reactions, forming negative ¬¬¬¬¬¬¬ions. gaining or losing electrons makes an atom an ____. gaining or losing ______ makes an atom an isotope. however, gaining or losing a ______ makes an atom into a completely different _________.
Upon combustion, a 0.8376 g sample of a compound containing only carbon, hydrogen, and oxygen produces 1.6003 gco2 and 0.9827 gh2o. find the empirical formula of the compound.
When two substances that cannot dissolve each other are mixed, a mixture is formed. a heterogeneous mixture that has very small dispersed particles and stays mixed for a long time is
a. a heterogeneous mixture that has larger dispersed particles that settle over time is
a?
When two substances that cannot dissolve each other are mixed, a mixture is formed. a heterogeneous mixture that has very small dispersed particles and stays mixed for a long time is a "Colloid"
An example of colloid can be gels, sols, or emulsions; where solids or liquids are dispersed in the mixture. It usually takes very long time to settle down.
Answer 2) SuspensionExplanation :A heterogeneous mixture that has larger dispersed particles that settle over time is a "Suspension"
Suspensions are those mixtures which usually has large particles and which takes comparatively less time than colloids to get settled. Like salt water, muddy water, fine sand in water, etc.
Answer:
First one is: heterogeneous
Second one is: colloid
Third one is: suspension
⛄️❆
Explanation:
is butter melting onto toast a chemical or a physical
Answer: "physical change" .
________________________________________________________
This would be a "physical change" . ________________________________________________________
Note: This would change from a "solid" to a "liquid" / mere rearrangement of molecules/ NOT a new chemical substance—hence, a "physical change".
________________________________________________________
A chemist requires 0.446 mol na2co3 for a reaction. how many grams does this correspond to?
Final answer:
To calculate the mass of 0.446 mol Na₂CO₃, multiply the number of moles by its molar mass of 105.98 g/mol, resulting in 47.27 grams of Na₂CO₃.
Explanation:
To find out how many grams 0.446 mol of Na₂CO₃ corresponds to, we can use the molar mass of Na₂CO₃.
First, we should recall the molar mass of Na₂CO₃. Using the atomic masses Na (22.99), C (12.00), and O (16.00), the molar mass would be:
(2 × 22.99) + 12.00 + (3 × 16.00) = 105.98 g/mol
Now, we can calculate the mass of 0.446 mol of Na₂CO₃:
0.446 mol Na₂CO₃ × 105.98 g/mol = 47.27 grams
How many valence electrons are in the trimethylammonium ion ch33nh+ ?
The trimethylammonium ion (CH3)3NH+ has a total of 25 valence electrons after accounting for its positive charge; 26 electrons from the combined valence electrons of nitrogen, carbon, and hydrogen atoms and subtracting one electron for the positive charge.
Explanation:To calculate the number of valence electrons in the trimethylammonium ion (CH3)3NH+, we first need to sum the valence electrons of all the atoms. Nitrogen (N) has 5 valence electrons, each hydrogen (H) atom has 1, and each carbon (C) atom has 4. Since there are three methyl groups (CH3), we have 3 carbons and 9 hydrogens:
Nitrogen: 5 valence electrons3 Carbons: 3 × 4 = 12 valence electrons9 Hydrogens: 9 × 1 = 9 valence electronsAdding these up gives 5 + 12 + 9 = 26 valence electrons. However, since we have a positively charged ion (NH+), we need to subtract one electron to account for the charge. This leaves us with a total of 25 valence electrons in the trimethylammonium ion. When drawing the Lewis structure of this polyatomic ion, it is also common practice to enclose the structure in brackets and denote the charge outside of it.
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The trimethylammonium ion, [tex](CH\(_3\))\(_3\)NH\(^+\)[/tex], has 0 valence electrons.
The trimethylammonium ion, [tex](CH\(_3\))\(_3\)NH\(^+\),[/tex]is composed of a nitrogen atom bonded to three methyl groups [tex](CH\(_3\))[/tex] and a hydrogen atom, with an additional positive charge indicating the loss of an electron compared to the neutral molecule.
First, let's consider the valence electrons in the neutral trimethylamine molecule, [tex](CH\(_3\))\(_3\)NH,[/tex] before it gains a positive charge:
Each hydrogen atom contributes 1 valence electron, and there are 12 hydrogen atoms in total (3 from each methyl group and 1 from the amine group), contributing 12 valence electrons.Each carbon atom contributes 4 valence electrons, and there are 3 carbon atoms in total (one in each methyl group), contributing 12 valence electrons.The nitrogen atom contributes 5 valence electrons. Adding these up gives us the total number of valence electrons in the neutral molecule: 12 (from hydrogen) + 12 (from carbon) + 5 (from nitrogen) = 29 valence electrons. Now, when the molecule gains a positive charge to become the trimethylammonium ion, it loses one electron. Therefore, the number of valence electrons in the ion is 29 - 1 = 28 valence electrons. However, the question asks for the number of valence electrons that are not involved in bonding, which is the definition of a lone pair. In the trimethylammonium ion, all of the valence electrons are involved in bonding: each hydrogen is bonded to a carbon or nitrogen, each carbon is bonded to three hydrogens and the nitrogen, and the nitrogen is bonded to three carbons and one hydrogen. There are no lone pairs of electrons on the nitrogen because it has formed four bonds, which means all eight of its valence electrons are involved in bonding.
Can someone eplain how to do this ? : identify the limiting reagent and the volume of CO2 formed when 11 L CS2 reacts with 18 L O2 to produce SO2 gas at STP. CS2(g)+3O2(g) → CO2(g)+2SO2(g),
The combustion of acetylene gas is represented by this equation: 2c2h2(g) + 5o2(g) → 4co2(g) + 2h2o(g) how many grams of co2 and grams of h2o are produced when 52.0 g c2h2 burn in oxygen?
A. The mass of CO₂ produced is 176 g.
B. The mass of H₂O produced is 36 g
We'll begin by calculating the mass of C₂H₂ that reacted and the masses of CO₂ and H₂O produced from the balanced equation.
2C₂H₂ + 5O₂ —> 4CO₂ + 2H₂O
Molar mass of C₂H₂ = (2×12) + (2×1) = 26 g/mol
Mass of C₂H₂ from the balanced equation = 2 × 26 = 52 g
Molar mass of CO₂ = 12 + (16×2) = 44 g/mol.
Mass of CO₂ from the balanced equation = 4 × 44 = 176 g
Molar mass of H₂O = (2×1) + 16 = 18 g/mol
Mass of H₂O from the balanced equation = 2 × 18 = 36 g
SUMMARY:
From the balanced equation above,
52 g of C₂H₂ reacted to produce 176 g of CO₂ and 36 g of H₂O.
From the above, we can see that 52 g of C₂H₂ produced:
176 g of CO₂36 g of H₂OLearn more about stoichiometry:
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How many moles of sodium acetate (nach3coo) must be added to 1.000 liter of a 0.500 m solution of acetic acid (ch3cooh) to produce a ph of 5.061? the ionization constant of acetic acid is 1.8 Ã 10â5 . answer in units of mol?
To create a buffer with a pH of 5.061 in a 0.500 M acetic acid solution, 0.545 mol of sodium acetate must be added to 1.000 liter of the solution. This calculation uses the Henderson-Hasselbalch equation and takes into account the ionization constant of acetic acid.
To find out how many moles of sodium acetate ([tex]NaCH_3COO[/tex]) must be added to 1.000 liter of a 0.500 M solution of acetic acid ([tex]CH_3COOH[/tex]) to produce a pH of 5.061, we can use the Henderson-Hasselbalch equation:
pH = pKa + log([A-]/[HA])
where [A-] is the concentration of the acetate ion, [HA] is the concentration of acetic acid, and pKa is the negative logarithm of the ionization constant (Ka) of acetic acid.
First, we calculate pKa:
pKa = -log(Ka)
pKa = -log(1.8 * 10-5)
pKa = 4.74
Next, rearrange the Henderson-Hasselbalch equation to solve for [A-]:
[A-] = [HA] * 10(pH-pKa)
[A-] = 0.500 M * 10(5.061-4.74)
[A-] = 0.500 M * 100.321
[A-] = 0.500 M * 2.09
[A-] \\approx 1.045 mol/L
Since the initial concentration of acetic acid is 0.500 M, we need to add 1.045 mol - 0.500 mol = 0.545 mol of sodium acetate to the solution to achieve the desired pH.
Which of these statements is not true?question 20 options:atoms of isotopes of an element have different numbers of protons.atoms of the same elements can have different masses.atoms are mostly empty space.the nucleus of an atom has a positive charge.save?
Explains why anyone in the classroom can hear that loud teacher across the hall even though the door is barley cracked open
A. Reflection
B. Refraction
C. Diffraction
PLEASE!! *MEASURING MATTER VOCAB MATCHING*
words:
1. matter
2. accuracy
3. precision
4. meniscus
5. volume
6. density
definitions:
- the mass of an object per unit volume
- anything that has mass and occupies space
- space occupied, measured in cubic units
- the degree to which a measurement can be replicated
- the curved top surface of a liquid column
- an indication of how close a measurement is to the correct result
MATCH THE WORDS TO THE DEFINITIONS PLEASE & THANK YOU!!
The words 'matter', 'accuracy', 'precision', 'meniscus', 'volume', and 'density' have been linked with their suitable definitions, clarifying their individual meanings.
Explanation:Here are the words matched to their definitions:
Matter: Anything that has mass and occupies space.Accuracy: An indication of how close a measurement is to the correct result.Precision: The degree to which a measurement can be replicated.Meniscus: The curved top surface of a liquid column.Volume: Space occupied, measured in cubic units.Density: The mass of an object per unit volume.Learn more about Vocabulary Matching here:https://brainly.com/question/29261631
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If the oxidation number of nitrogen in a certain molecule changes from +3 to -2 during a reaction, is the nitrogen oxidized or reduced? how many electrons are gained or lost by the nitrogen atom?
Since here we can see that there is a negative -2 charge on nitrogen so there is gain of electron and hence it is reduced.
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Which of the following is a benefit of having a standard measurement system that can be used by scientists worldwide?
1. Scientists can all perform different experiments
2. Scientists can compare and share data with each other.
3. Scientists never have to report their results.
4. Scientists can save their data for future experiments.
I think the answer is answer #2. Is this correct?,
how much water vapor can a cubic meter of air hold at 25 degrees celcius