Dmitri Mendeleev was the first to publish the classification of the elements that is the basis of our current Periodic Table, by grouping them in order of atomic weight and similar chemical properties in 1869.
Explanation:The classification of the elements that is the basis of our periodic table today was first published by Dmitri Mendeleev in 1869. Mendeleev's table, also known as the Mendeleev periodic table, was the first to order the elements by atomic weight and to group them based on their chemical properties. Mendeleev even left vacant spaces in his table for elements that he predicted would be discovered in the future. His predictions were remarkably accurate and gave rise to the systematic table we use today.
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In a flame test experiment, Sodium gives the brightest and most persistent colour in the flame. Do you think that Potassium could be detected visually in the presence of Sodium, by heating this mixture in a flame? Explain your answer.
Yes, it is possible to visually detect the presence of potassium, even though sodium produces a brighter and more persistent color.
In a flame test experiment, the color observed in the flame is due to the excitation and subsequent relaxation of electrons in atoms or ions.
Each element has a unique set of energy levels, and when the electrons transition between these levels, they emit light of specific wavelengths, which we perceive as colors.
To enhance the visibility of potassium's flame color, one could adjust the experimental conditions, such as using a higher concentration of potassium or reducing the concentration of sodium.
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Final answer:
Potassium can be detected in the presence of sodium during a flame test by looking for its characteristic lilac color. Special equipment like spectrometers can enhance the detection of potassium's color in the flame test.
Explanation:
In a flame test experiment, when sodium is present, it can overwhelm other colors due to its bright yellow flame, which is highly persistent and intense. However, potassium can still be detected visually in the presence of sodium in a flame test. Potassium imparts a lilac color to the flame, which can be observed at the moment when the sodium's yellow emission fades, or by observing the edge of the flame where the color may be less intense. Additionally, the use of spectrometers or filters can help in better visualizing the potassium flame in the presence of sodium.
1) The spectrum of lithium has a red line of 670.8 nanometers. (Remember 1 m = 1 X 109 nm) a. Convert the nanometer to meter using dimensional analysis. b. Calculate the frequency of the wave. c. Calculate the energy of a photon with this wavelength.
calculate the frequency of red light with a wavelength of 6.50x10^-7
How many atoms are in 2.70 moles of iron (Fe) atoms?
4.48 × 10-24 atoms Fe
1.63 × 1024 atoms Fe
2.23 × 1023 atoms Fe
6.02 × 1023 atoms Fe
Avogadro's number is the number of units (atoms, molecules) in 1 mole of substance:
6.023 × 10²³ atoms per 1 moleThe 64.8-g sample of the compound X2O5 contains 48.0 g of oxygen atoms. What is the molar mass of element X?
7.The _____ theory of matter states that all particles of matter are in constant motion.
(Fill in the blank)
The kinetic theory of matter states that all particles of matter are in constant motion.
The following are the postulates of kinetic theory of gases:
1. The particles of gases are in constant and random motion. Due to this motion, they collide with each other and walls of the container.
2. The particles of gases have point mass and zero volume.
3. The particles of gases have no such attraction or repulsion between them.
4. The kinetic energy with which the particles are moving is directly proportional to temperature. A temperature increases, kinetic energy also increases, and particles collide each other more frequently.
5. The particle of gases at given temperature have same kinetic energy.
2. In a molecule represented by the chemical formula C6H12O6, how many atoms of each element are present?
C6H12O6 is sugar.
There are:
6 C (carbon atoms),
12 of H (hydrogen atoms),
6 of O (oxygen atoms).
Helium is used in balloons because it is
a. reactive with rubber.
b. lighter than air.
c. flammable.
d. a colored gas
Final answer:
Helium is used in balloons because it is lighter than air and safely floats due to its low density and nonreactive, nonflammable properties. So the correct option is b.
Explanation:
Helium is used in balloons because it is lighter than air. This is due to helium's much lower density and atomic mass compared to the average molar mass of air. Helium's atomic mass is approximately 4.00 g/mol, while air has an average molar mass of about 29 g/mol. Hence, when a balloon is filled with helium, it floats. Another critical property of helium that makes it the gas of choice for balloons is its nonreactivity. Helium is chemically non-reactive and nonflammable, which contrasts with hydrogen, another light gas that is, however, highly flammable. This property of helium makes it safe for use in various applications like balloons, airships, and blimps. Furthermore, in environments where there is a high risk of fire or explosion, such as in welding, helium serves as an inert protective atmosphere. Finally, for deep-sea divers who operate under high pressure, a mixture of oxygen and helium is essential to avoid nitrogen narcosis, commonly known as the “rapture of the deep”.
As the concentration of a given salt solution increases, the conductivity of the solution:
a) increases
b) no way to predict
c) remains the same
d) increases then decreases
decreases ...?
Answer: Option (a) is the correct answer.
Explanation:
Conductivity of a solution depends number of ions present in the solution. As these ions move from one place to another and thus there will be easily flow of current.
So, when there is increase in concentration then it means there are moer number of ions present into the solution.
Thus, conductivity will also increase due to increase in concentration of salt solution.
an ore contains a mixture of zinc carbonate and lead carbonate. Zinc and lead are produced from this ore by 2 reactions.
REACTION 1: The carbonates in the ore are converted into a mixture of zinc oxide and lead oxide
Name this type of reaction. ______________________
How is this reaction done? _______________________
REACTION 2: the metals are mixed with carbon and heated in a furnace to produce zinc and lead
Explain why zinc and lead are produced ...?
Answer: the ore undergoes a decomposition reaction to convert the carbonates into metal oxides, and then a reduction reaction to produce the pure metals zinc and lead.
Explanation:
The type of reaction in which the carbonates in the ore are converted into a mixture of zinc oxide and lead oxide is called a decomposition reaction.
In this reaction, the zinc carbonate and lead carbonate compounds are broken down into their respective metal oxides, zinc oxide and lead oxide. This is achieved by heating the ore, which provides the energy needed to break the chemical bonds in the carbonates.
The decomposition reaction is represented by the following chemical equation:
ZnCO3 (zinc carbonate) → ZnO (zinc oxide) + CO2 (carbon dioxide)
PbCO3 (lead carbonate) → PbO (lead oxide) + CO2 (carbon dioxide)
The second reaction, known as reduction, involves mixing the metal oxides (zinc oxide and lead oxide) with carbon and heating them in a furnace. This process is known as smelting.
During smelting, the carbon acts as a reducing agent, meaning it removes the oxygen from the metal oxides. This reduction reaction converts the metal oxides into their respective pure metals, zinc and lead. The carbon combines with oxygen to form carbon dioxide.
The reduction reaction can be represented by the following chemical equation:
ZnO (zinc oxide) + C (carbon) → Zn (zinc) + CO (carbon monoxide)
PbO (lead oxide) + C (carbon) → Pb (lead) + CO (carbon monoxide)
Zinc and lead are produced because the smelting process separates the metal atoms from the oxygen atoms in the metal oxides. This is possible because carbon has a higher affinity for oxygen than zinc and lead do. As a result, the carbon reacts with the oxygen, leaving behind the pure metals.
what property do atoms of these elements have that helps make the molecules polar
Suppose you wanted to calculate the heat of reaction for the formation of ammonia gas and gaseous hydrochloric acid from solid ammonium chloride.
a. Write a balanced equation for this reaction.
Answer:
Above is correct, but the heat of reaction is 176.18 J/mol
Explanation:
A dilute, aqueous potassium nitrate solution is best classified as a
(1) homogeneous compound
(2) homogeneous mixture
(3) heterogeneous compound
(4) heterogeneous mixture
A dilute, aqueous potassium nitrate solution is classified as a homogeneous mixture, as it is a uniform mixture of solute and solvent at the molecular level.
Explanation:A dilute, aqueous potassium nitrate solution is best classified as a (2) homogeneous mixture, also known as a solution. This classification is due to the fact that potassium nitrate is a highly soluble ionic compound that, when dissolved in water, dissociates into ions, creating a mixture with a composition that is uniform throughout. Therefore, it is not possible to distinguish between the different components of the mixture, even with a powerful microscope. If we were talking about potassium hydroxide, it would similarly be fully soluble and dissociate completely, yielding a specified concentration of hydroxide ions in the case given. Nevertheless, for potassium nitrate, the dissolution would result in potassium and nitrate ions evenly distributed in the solution.
what is the mass of 5 moles of Fe203?
To find the mass of 5 moles of Fe₂O₃, multiply its molar mass (159.70 g/mol) by 5, resulting in 798.5 grams. This calculation uses the molar mass of the elements iron and oxygen.
To find the mass of 5 moles of Fe₂O₃, we need to use the molar mass of the compound. Fe₂O₃ has the following molar mass:
Fe: 55.85 g/mol
O: 16.00 g/mol
Since there are 2 iron atoms and 3 oxygen atoms in Fe₂O₃, the calculation is:
2 × 55.85 g/mol + 3 × 16.00 g/mol = 159.70 g/mol
Now, multiply the molar mass by the number of moles:
159.70 g/mol × 5 mol = 798.5 g
Therefore, the mass of 5 moles of Fe₂O₃ is 798.5 grams.
Francium has the largest atomic radius. Why might this be?
A. The highest number of protons for the least number of electrons and neutrons.
B. The highest number of energy levels and the least nuclear pull.
C. The lower ability to gain or lose electrons resulting in fewer ions forming.
D. The highest number of energy levels most nuclear pull.
Francium has the largest atomic radius due to having the highest number of energy levels and the least nuclear pull.
Explanation:The correct answer is B. Francium has the largest atomic radius because it has the highest number of energy levels and the least nuclear pull. The atomic radius refers to the size of an atom, which is determined by the distance between the nucleus and the outermost electron shell.
Francium has the highest number of energy levels, which means the electrons are located farther from the nucleus, resulting in a larger atomic radius. Additionally, francium has the least nuclear pull, meaning the positive charge of the nucleus has less of an attraction on the outermost electrons, allowing them to spread out more.
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Examine the equation.
CH4 + 2O2 → CO2 + __H2O
In order to balance the equation, what coefficient must be placed in front of H2O?
2
4
1
3
Answer:
[tex]\huge \boxed{\mathrm{2}}[/tex]
[tex]\rule[225]{225}{2}[/tex]
Explanation:
[tex]\sf CH_4+ O_2 \Rightarrow CO_2 + H_2O[/tex]
Balancing the Hydrogen atoms on the right side,
[tex]\sf CH_4+ O_2 \Rightarrow CO_2 +2 H_2O[/tex]
Balancing the Oxygen atoms on the left side,
[tex]\sf CH_4+ 2O_2 \Rightarrow CO_2 +2 H_2O[/tex]
[tex]\rule[225]{225}{2}[/tex]
Give the electron configuration for a neutral atom of manganese. Atomic number of Mn is 25.
If approximately equal volumes of an acid and a base of equal strengths are combined, the resulting solution should have a pH of _____.
Answer : The resulting solution will have a pH of 7.
Explanation:
Whenever acid and base reacts with each other to form water molecule is called Neutralization reaction. This water molecules is formed from the hydronium ion ([tex]H^+[/tex]) from acid and hydroxide ion([tex]OH^-[/tex]) from base.
When the equal volumes of acid and base of equal strength are combined, the resulting pH of the solution becomes 7.
The pH 7 value means that the solution is neutral.
Which coefficients balance the following equation __ N2+___H2--->___NH3
Which of the following elements would be the least likely to form a cation if involved in a chemical reaction?
chlorine (Cl)
potassium (K)
nitrogen (N)
fluorine (F)
Answer:
Fluorine (F) would be least likely to form a cation
Explanation:
A cation is a positively charged atom (or molecule) which has lost electron (or electrons). Electropositive elements show a greater propensity to lose electrons and form cations. These are usually metals that are present on the left of the periodic table.
Electropositivity or the tendency to lose electrons and form cations increases on going down a group and decreases across a period. In the given examples:
Potassium, K is an alkali metal and will lose electrons readily to form a cation
Nitrogen (N), Fluorine (F) and chlorine (Cl) are all non metals which prefer to accept electrons and form anions instead. Among the three, F is the most electronegative i.e. it will prefer to accept electrons and form F- rather than F+.
What physical force can cause a change in the state of matter?
1.Which best explains why ionization energy tends to decrease from the top to the bottom of a group?
A.The number of orbitals decreases.
B.The number of neutrons decreases.
C.Electrons get closer to the nucleus.
D.Electrons get farther from the nucleus.
3.When electrons are removed from the outermost shell of a calcium atom, the atom becomes
A. an anion that has a larger radius than the atom.
B. an anion that has a smaller radius than the atom.
C. a cation that has a larger radius than the atom.
D. a cation that has a smaller radius than the atom.
Answer:
1) Electrons get farther from the nucleus.
2) a cation that has a smaller radius than the atom.
Explanation:
1) ionization energy is the energy required to remove the valence electron from an isolated gaseous atom of an element.
Thus it requires some energy to remove the electron as electrons are attracted towards nucleus (positive protons are present) due to nuclear charge.
As the size increases on moving top to bottom (due to more number of shells) the distance of electrons from the nucleus increases which decreases the effective nuclear charge on electrons, decreasing the ionization energy.
2) When an atom loses an electron it attains a positive charge and is known as cation.
A cation has smaller size than the neutral atom as the less electrons are attracted towards nucleus and thus feel more effective nuclear charge.
The answers are 1. The ionization energy tends to decrease from the top to the bottom of a group because D. Electrons get farther from the nucleus. 3. When electrons are removed from the outermost shell of a calcium atom, the atom becomes D. a cation that has a smaller radius than the atom.
The correct answer for question 1 is D. Electrons get farther from the nucleus best explains why ionization energy tends to decrease from the top to the bottom of a group
Ionization energy is the energy required to remove an electron from an atom in the gaseous state. As one moves down a group in the periodic table, the ionization energy tends to decrease. This is because each element down the group has an additional shell of electrons. The outermost electrons are farther from the nucleus, which means they experience a weaker effective nuclear charge. The increased distance from the nucleus and the screening effect of the inner electrons make it easier to remove an outer electron, thus decreasing the ionization energy.
The incorrect options can be explained as follows:
A. The number of orbitals increases, not decreases, as one moves down a group, which actually contributes to the decrease in ionization energy.
B. The number of neutrons generally increases as one moves down a group, but this does not directly affect the ionization energy.
C. Electrons do not get closer to the nucleus; in fact, they get farther away as additional electron shells are added, which is why the ionization energy decreases.
The correct answer for question 3 is D. a cation that has a smaller radius than the atom.
When electrons are removed from an atom, the atom becomes a cation (a positively charged ion). In the case of calcium, which has two electrons in its outermost shell, removing these electrons results in a Ca^2+ ion. Because the outermost electrons are no longer there to shield the nuclear charge, the remaining electrons are more strongly attracted to the nucleus. This causes the ion to have a smaller radius than the neutral atom.
The incorrect options can be explained as follows:
A. An anion is formed when an atom gains electrons, not when electrons are removed.
B. An anion would have a larger radius than the neutral atom because the added electrons increase repulsion and decrease the effective nuclear charge.
C. A cation has a smaller radius than the neutral atom, not a larger one, because the loss of electrons increases the effective nuclear charge, pulling the remaining electrons closer to the nucleus."
What mass of CCl4 is formed by the reaction of 5.14 g of methane with an excess of chlorine?
[tex]\boxed{{\text{49}}{\text{.224 g}}}[/tex] of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is produced by the reaction of 5.14 g of methane with an excess of chlorine.
Further explanation:
Stoichiometry of a reaction is used to determine the amount of species present in the reaction by the relationship between the reactants and products. It can be used to determine the moles of a chemical species when the moles of other chemical species present in the reaction is given.
Consider the general reaction,
[tex]{\text{A}} + 2{\text{B}}\to3{\text{C}}[/tex]
Here,
A and B are reactants.
C is the product.
One mole of A reacts with two moles of B to produce three moles of C. The stoichiometric ratio between A and B is 1:2, the stoichiometric ratio between A and C is 1:3 and the stoichiometric ratio between B and C is 2:3.
Limiting reagent:
A limiting reagent is the one that is completely consumed in a chemical reaction. The amount of product formed in any chemical reaction has to be in accordance with the limiting reagent of the reaction. The amount of product depends on the amount of limiting reagent since the product formation is not possible in the absence of it.
The given reaction occurs as follows:
[tex]{\text{C}}{{\text{H}}_4}\left(g\right) + 4{\text{C}}{{\text{l}}_2}\left(g\right)\to{\text{CC}}{{\text{l}}_4}\left(g\right)+4{\text{HCl}}\left(g\right)[/tex]
It is given that chlorine is present in an excess amount so methane [tex]\left({{\text{C}}{{\text{H}}_4}}\right)[/tex] is a limiting reagent and therefore it controls the amount of [tex]{\text{CC}}{{\text{l}}_4}[/tex] produced during the reaction.
The formula to calculate the amount of [tex]{\text{C}}{{\text{H}}_4}[/tex] is as follows:
[tex]{\text{Amount of C}}{{\text{H}}_4} = \frac{{{\text{Given mass of C}}{{\text{H}}_{\text{4}}}}}{{{\text{Molar mass of C}}{{\text{H}}_{\text{4}}}}}[/tex] …… (1)
The given mass of [tex]{\text{C}}{{\text{H}}_4}[/tex] is 5.14 g.
The molar mass of [tex]{\text{C}}{{\text{H}}_4}[/tex] is 16.04 g/mol.
Substitute these values in equation (1).
[tex]\begin{aligned}{\text{Amount of C}}{{\text{H}}_4} &= \left({{\text{5}}{\text{.14 g}}}\right)\left({\frac{{{\text{1 mol}}}}{{{\text{16}}{\text{.04 g}}}}}\right)\\ &= 0.32044\\&\approx{\mathbf{0}}{\mathbf{.320 mol}}\\\end{aligned}[/tex]
From the balanced chemical reaction, it is clear that 1 mole of [tex]{\text{C}}{{\text{H}}_4}[/tex] produces 1 mole of [tex]{\text{CC}}{{\text{l}}_4}[/tex] .
So the amount of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is equal to that of [tex]{\text{C}}{{\text{H}}_4}[/tex] and thus the amount of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is 0.320 mol.
The formula to calculate the mass of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is as follows:
[tex]{\text{Mass of CC}}{{\text{l}}_4} = \left( {{\text{Moles of CC}}{{\text{l}}_4}}\right)\left({{\text{Molar mass of CC}}{{\text{l}}_4}}\right)[/tex]
…… (2)
The number of moles of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is 0.320 mol.
The molar mass of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is 153.82 g/mol.
Substitute these values in equation (2).
[tex]\begin{gathered}{\text{Mass of CC}}{{\text{l}}_4} = \left({{\text{0}}{\text{.320 mol}}}\right)\left({\frac{{{\text{153}}{\text{.82 g}}}}{{{\text{1 mol}}}}}\right)\\ = {\mathbf{49}}{\mathbf{.224 g}}\\\end{gathered}[/tex]
Therefore, the mass of [tex]{\text{CC}}{{\text{l}}_4}[/tex] produced is 49.224 g.
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1. Calculate the moles of chlorine in 8 moles of carbon tetrachloride: https://brainly.com/question/3064603
2. How many grams of potassium were in the fertilizer? https://brainly.com/question/5105904
Answer details:
Grade: Senior School
Subject: Chemistry
Chapter: Mole concept
Keywords: stoichiometry, reactant, product, limiting reagent, CCl4, CH4, Cl2, molar mass, given mass, amount of CH4, amount of CCl4, 49.224 g, mass of CCl4, 4Cl2, 4 HCl, 5.14 g, 16.04 g/mol.
Milk of magnesia is _____.
an acid
a base
a neutral
Final answer:
Milk of magnesia is a base with a pH greater than 7, specifically around 10.5, making it effective as an antacid. It contrasts with neutral substances, like water, and acidic substances, like wine.
Explanation:
Milk of magnesia is a base. This determination is based on its pH level, which is greater than 7. Specifically, milk of magnesia, which is largely comprised of magnesium hydroxide (Mg(OH)2), has a pH of approximately 10.5. This high pH level classifies it as a basic substance, meaning it has properties that counteract acids. This characteristic is why milk of magnesia is commonly used as an antacid to neutralize stomach acid and alleviate symptoms of indigestion and heartburn.
In comparison, substances with a pH of 7, such as pure water, are considered neutral, neither acidic nor basic. Substances like wine, with a pH less than 7, are classified as acidic. Understanding the pH scale and the properties of acids and bases is essential in chemistry and various practical applications, including medicine and nutrition.
What element behaves MOST like magnesium
between Si, S, Sr, Sn
Answer
SrExplanation
In periodic table, the elements have almost same properties are present in the same group. As Mg and Sr are present in group II-A, so both behave most likely to each other due to having same valence shell electrons as well.Si and Sn are present in group IV-A which have same behavior but different one from Mg due to different groups.S is present in group VI-A which show different properties from all others one especially from Mg.Calculate the Cal(kcal) in 1 cup of whole milk: 12 g of carbohydrate, 9 g of fat, and 9 g of protein.
Answer:
165Kcal in a cup of whole milk
Explanation:
Hello! Let's solve this!
We know that 1g
carbohydrate = 4 Kcal
1g protein = 4Kcal
1g fat = 9Kcal
We do the conversion of each one
carbohydrates = 12g * 4Kcal * g = 48Kcal
Proteins = 9g * 4Kcal / g = 36Kcal
fat = 9g * 9Kcal / g = 81Kcal
We add all the results to have the total Kcal
48Kcal + 36Kcal + 81Kcal = 165Kcal in a cup of whole milk
what is the law of conservation of mass? how is it related to balancing chemical equations
This graph shows the concentration of the reactant A in the reaction A→B.
Determine the average rate of the reaction between 0 and 10 seconds.
0.007 M/s
0.014 M/s
0.86 M/s
0.07 M/s
Answer:
0.014 M/s
Explanation:
The rate of a reaction depends on the concentration of a particular compound and it stoichmetry coefficient. For the reaction:
aA + bB → cC +dD
The rate can be calculated:
r = -(1/a)xΔ[A]/Δt = -(1/b)xΔ[B]/Δt = (1/c)xΔ[C]/Δt = (1/d)xΔD/Δt
The minus signal for the reagents its because they are being consumed, so Δ[A] and Δ[B] will be negative, and r must be positive. Δt is the time variation.
So, for the reaction given, in t = 0, [A] =1 M, and in t= 10s, [A] = 0.86 M, then
Δ[A] = -0.14 M
r = -(Δ[A]/Δt)
r = -(-0.14/10)
r = 0.014 M/s
Which type of atom has the strongest attraction for electrons in bond formation? barium (Ba) chlorine (Cl) iodine (I) strontium (Sr)
Answer: Chlorine has the strongest attraction for electrons in bond formation.
Explanation:
Chlorine is highly electronegative as compared to iodine and has high electron gain enthalpy. So, it will readily accept an electron in order to complete its octet. The electronegativity decreases down the group from Cl to I, and hence the tendency to gain an electron decreases.
In case of Barium, and Strontium there are completely filled sub shells and therefore the tendency to gain an electron is the least.
Thus, it can be concluded that chlorine has the strongest attraction for electrons in bond formation.
Kumar is producing the photoelectric effect by using red light. He wants to increase the energy of emitted electrons. Based on the research of Albert Einstein, what is the best way for him to do this?
Explanation:
Photoelectric effect: Electrons are ejected out from the surface of metal when light of sufficient frequency falls upon shiny surface of metals. light is made up small bundles of energy packets named photons which when falls on surface transfer their energy to electrons due which electrons ejects out of the metallic surface. The energy for one photon was given by expression:
E=h[tex]\nu[/tex], or [tex]E\propto \nu[/tex]
h=Planck's constant, [tex]\nu[/tex]= frequency of the light
Kumar can increase the energy of emitted electron by using light with higher value of frequency than the frequency of red light. This is because the energy carried by the photon of a light is directly proportional to the frequency of the light. Higher the value of frequency of light higher will be the value of energy of a photon. And photon with higher energy will impart more amount of energy to an electron while ejection.