The pKb value for aqueous ammonia at 25


is 4.8.


What is the correct pKa value for the ammonium ion at this temperature? (Kb denotes the base dissociation constant and Ka denotes the acid dissociation constant.)

Answer:

okay

Explanation:

9 . acidic

10.  hydrogen

answer the following questions

11. Gold as a precious metal is used widely in making jewelry items. This metal is preferred over others for jewelry pieces for various reasons. One important reason for its popularity is that it does not react with atmospheric moisture and therefore, it does not rust.

12. corrosion is defined as rust it's due to humidity and moisture

13. Sulphur appears much below chlorine in the reactivity table and cannot displace chlorine from dilute HCl.

14. Highly conductive metal

Surpassed only by silver, copper is a highly conductive metal. This means electricity can pass through it with greater ease, making it ideal for use in electrical wires. Companies can use other conductive metals to create electrical wires.

15. Corrosion

Copper metal when exposed to air turns green in color due to corrosion. When the copper vessel is exposed to air in the rainy season, the metal reacts with gases, moisture, and atmospheric gases to form a mixture of copper carbonate and copper hydroxide. This gives a green color to the surface of the copper meta

16. Silicon

silicon is the backbone of the electronics industry. Because silicon is the reason for the fast development happened in the field of electronics. therefore, silicon is the backbone of electronics.

17. High chemical reactivity

Sodium is stored under kerosene because of its high chemical reactivity with almost all of the other elements (for example oxygen from the air which oxidizes it instantly). Kerosene and mineral oil are the only chemicals that make sodium inert. Usually, when Na reacts with a solvent it liberates hydrogen gas from its composition.

18. Metal oxides are oxides of metals. Nonmetal oxides are oxides of nonmetals. The main difference between metal oxides and nonmetal oxides is that metal oxides are basic compounds whereas nonmetal oxides are acidic compounds.

19.  Silver is more likely to tarnish near a petroleum refinery than in a place far away from it because when silver reacts with petroleum or hydrogen sulfide present in it as a pollutant in the air, it starts forming a black coating of silver sulfide.

20. A noble metal is ordinarily regarded as a metallic chemical element that is generally resistant to corrosion and is usually found in nature in its raw form. Gold, platinum, and the other platinum group metals (ruthenium, rhodium, palladium, osmium, iridium) are most often so classified. Silver, copper, and mercury are less often to sometimes included as noble metals although each of these usually occurs in nature combined with sulfur.

Answer:

1.05 mols of O2 gas

Explanation:

For this type of problem, it's important to understand what the balanced Chemical equation tells us:

Let's look at the balanced chemical equation:

[tex]2Mg(s)+O_2(g)-- > 2MgO(s)[/tex]

This equation two sides of the reaction arrow.  On the left are the reactants (things you start with, and that react during the chemical reaction), and on the right side are products (things that are produced during the chemical reaction that you end with).

The numbers in front of each compound tell how many of molecules are involved for a full reaction without anything left over.  A "mol" is a large quantity ([tex]6.022*10^{23}[/tex]), in this case, of molecules , since it's unlikely you're only taking a single molecule of each substance (it would be so tiny, you wouldn't even know you were doing the reaction).

So,for every 2 moles of Magnesium used, we'll also need 1 mole of Oxygen, and it will produce 2 moles of Magnesium Oxide.

In a way, during the reaction it's almost like 2 moles of Magnesium is equal to 1 mole of Oxygen and is equal to 2 moles of Magnesium Oxide:

[tex]2 mol Mg(s)=1mol O_2(g)=2molMgO(s)[/tex]

From here, we can build some unit ratios, to convert between the known quantity of moles we have, and find the unknown quantity of moles that are requested.

We know that we are looking at 2.10 mol of Magnesium, so we want a unit ratio with moles of Mg on the bottom.  We want to find moles of O2, so we want a unit ratio of moles of O2 on top.

The unit ratio we want is the middle part of the equation, divided by the left part of the equation.

[tex]2 mol Mg(s)=1mol O_2(g)\\\frac{2 mol Mg(s)}{2 mol Mg(s)}=\frac{1mol O_2(g)}{2 mol Mg(s)}\\1=\frac{1mol O_2(g)}{2 mol Mg(s)}[/tex]

Since this quantity is 1, it is a unit ratio and can be multiplied to other things to change their units (for this problem).

Starting with what we know, and multiplying by our unit ratio:

[tex]2.10 mol Mg(s)*\frac{1mol O_2(g)}{2 mol Mg(s)}=1.05mol O_2(g)[/tex]

Notice that the units from the first quantity cancel with the units on the bottom of the fraction, leaving only the unit on top of the fraction ... the exact units we wanted!

So, 1.05mols of O2 would be consumed during the reaction if exactly 2.10moles of Magnesium are burned.

The frequency of the green light emitted by a hydrogen atom with a wavelength of 525 nm is [tex]5.71[/tex]×[tex]10^{14} s^{-1}[/tex]

What is wavelength?

What is a frequency?

Wavelength=525nm

The relation between wavelength and frequency

[tex]v=\frac{c}{lambda}[/tex]

[tex]v=[/tex]frequency

[tex]c=[/tex]speed of light = [tex]3.0[/tex]×[tex]10^{8}[/tex][tex]m/sec[/tex]

λ(lambda)=wavelength

substitute the value in the equation mentioned above

[tex]v=3.0[/tex]×[tex]10^{8}[/tex][tex]/525[/tex]×[tex]10^{-9}[/tex]

[tex]=5.71[/tex]×[tex]10^{14}[/tex][tex]s^{-1}[/tex]

hence, the frequency of the green light emitted by a hydrogen atom with a wavelength of 525 nm is [tex]5.71[/tex]×[tex]10^{14} s^{-1}[/tex]

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The electroplating process of the coin results in the coating of the coin with copper metal.

Electroplating is the process of using coating the surface of a metal with another one electrolytic cell.

The electroplating of the coin is done using copper as the anode and the coin as the cathode. The electrolyte is copper sulfate solution.

Oxidation occurs at the anode with the copper metal being converted to copper (ii) ions.

Reduction occurred at the cathode as the copper (ii) ions in the solution accept electrons to become copper metal and the coin being coated with copper.

The half-reactions are shown below:

At the anode:

[tex]Cu(s) \rightarrow Cu^{2+}(aq) + 2e^{-}[/tex]

At the cathode:

[tex]Cu^{2+}(aq) + 2e{-} \rightarrow Cu(s)[/tex]

Therefore, the electroplating process of the coin results in the coating of the coin with copper metal.

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Answer:

A device in which oil can be trapped, or which makes use of oil to trap something else I think

Answer:

44.01 g/mol

Explanation:

Carbon dioxide is produced when carbon and oxygen are burned.

To totally burn carbon into carbon dioxide, or CO2, we require one mole of oxygen for every gram of carbon by weight.

or alternatively:

You produce 12+216=44 g of carbon dioxide for every 12 g of carbon.

The weight of CO2 in kg may be calculated if the amount of CO2 in litres is known by converting it to moles and multiplying it by 44.

The moles of nitrogen produced is 0.40 moles of ammonia.

The Percent yield of ammonia is 81.2%

The moles of ammonia produced is obtained from the mole ratio of the reaction.

The mole ratio of hydrogen to nitrogen is 3 : 2

Based on the mole ratio, the limiting reactant is hydrogen.

Moles of nitrogen produced = 0.600 * 2/3 = 0.40 moles of ammonia.

mass of ammonia expected = 0.4 * 17 g = 6.8 g

Percent yield = 5.52/6.8 * 100% = 81.2%

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Answer: Double replacement reaction

Explanation:

The production of ammonia will be favored at high pressure and low temperature.

The term exothermic reaction has to do with a reaction in which the forward reaction is favored at lower temperatures.

Now looking at the reaction coordinate and the equation of the reaction, we know that the production of ammonia will be favored at high pressure and low temperature.

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Your question's data is not correct, it should be 100 grams of limestone instead of 10 grams, You will find the correct solution below according to that.

The percentage purity of calcium carbonate is 82.5%

The balanced chemical equation is

CaCO₃ + 2HCl  →  CaCl₂ + H₂O + CO₂

Because CO₂ is a gas, you can easily convert it to mole directly

No. of mol of CO₂ = volume dm³ /22.4 dm³

No. of mol of CO₂ = 8.5 dm³ / 22.4 dm³

No. of mol of CO₂ = 0.825 mol

According to equation 1 mole of CO2 is made from 1 mole of CaCO3

So, 0.825 mole of CO2 will be made from 0.825 mole of CaCO3

Mass of CaCO3 = moles of CaCO3 × Molar mass of CaCO3

Mass of CaCO3 = 0.825 × 100 grams

Mass of CaCO3 = 82.5 grams

Percentage purity of CaCO3 = (mass of CaCO3/Total mass of CaCO3) × 100

Percentage purity of CaCO3 = (82.5/100) × 100 %

Percentage purity of CaCO3 = 82.5 %

Thus we can say that as percentage purity is the percentage of mass of pure compound on per unit of total compound, the percentage purity of the calcium carbonate will be 82.5 %

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Answer:

The total number of electrons in a valence shell is called valence electrons. The electron configuration of rubidium shows that the last shell of rubidium has an electron. Therefore, the valence electrons of rubidium(Rb) are one.

Compared to infrared radiation, an electromagnetic wave that has a lower frequency will also have a longer wavelength and equal speed

Electromagnetic waves or EM waves are waves that are created as a result of vibrations between an electric field and a magnetic field.

It can be also defined as waves are composed of oscillating magnetic and electric fields.

One important feature fo electromagnetic radiation is that all have the same speed in vacuum, c, in vacuum, which is the speed of light.

Since, the speed, wavelength and frequency of the waves are related you can infere any of them when the other two are known.

The equation is:

speed = frequency × wavelength

   s     =          ν        ×      λ

   c     =          ν        ×      λ      . . . for the specific case of electromagnetic radiation

That inverse relation between frequency and wavelength, where the speed is the constant, shows that the lower the frequency the longer the wavelength.

Therefore,  the correct statment is that an an electromagnetic wave that has a lower frequency will also have a longer wavelength and equal speed (option B).

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Answer:

7.22 x 10¹⁰ ng Ni

Explanation:

To find the mass of nickel, you need to (1) convert moles to grams (via atomic mass from the periodic table) and then (2) convert grams to nanograms. These ratios need to be multiplied by each other, starting with the given value. It is important to arrange the conversions/ratios in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 3 sig figs to reflect the given value (1.23).

Atomic Mass (Ni): 58.693 g/mol

1 gram = 1 x 10⁹ nanograms

1.23 moles Ni             58.693 g               1 x 10⁹ ng
----------------------  x  ----------------------  x  ---------------------  =  7.22 x 10¹⁰ ng Ni
                                     1 mole                       1 g

C12H24O2 +17 O2-------->12CO2 + 12H2O

combustion is a chemical reaction that often involves the presence of oxygen and produces heat and light in the form of flames.

Lauric acid has a 12-carbon backbone and is a saturated medium-chain fatty acid. In addition to being a key component of coconut oil and palm kernel oil, lauric acid occurs naturally in a variety of plant and animal fats and oils.

White solid lauric acid has a little bay oil odour to it.

Lauric acid is a cheap, non-toxic, and easy-to-handle substance that is frequently employed in lab studies on melting-point depression. Because lauric acid is a solid at ambient temperature but a liquid at boiling temperatures, it can be used to test different solutes to determine their molecular weights.

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Answer:

187.416 M/s

Explanation:

First the units    M^-2 s^-1   *  M^3   =  M/s

now the numbers

3700 * .37^3 = 187.416

Answer:

Sulfur dioxide (SO2)

⇒ Why is this the best option?

To determine the polarity of the molecule, there are two requirements. The first one has a variety of terminal atoms, whereas the second has a lone pair on the center atoms. The molecule is polar if one of the requirements is met; else, it is nonpolar. The oxygen atom is a terminal atom because it surrounds the sulfur atom, which is the center element in the SO2 molecule's Lewis structure. In this molecule, there are two terminal oxygen atoms. If we look at the first criterion, we can see that it is not met because it calls for the presence of two separate terminal atoms.

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Answer: Understanding oxidation-reduction reactions

Explanation:

Rusting occurs when electrons are exchanged between iron and oxygen.

Answer:

a. Physical Chemistry

b.Organic Chemistry

c.Food analysis, a very important branch of analytical chemistry

d. Biochemistry

Explanation:

Answer:

Place 20.0 g NaOH(s) in a flask and dilute to 1.00 L with water.

Explanation:

Answer:

0.12 M

Explanation:

To find the new concentration, you need to (1) find the moles of Solution A (via the molarity equation), then (2) find the moles of Solution B, then (3) combine all of the moles and volumes, and then (4) calculate the new molarity. The final answer should have 2 sig figs to reflect the lowest amount of sig figs in the given values.

Solution A:

7.7 mL / 1,000 = 0.0077 L

Molarity = moles / volume

0.10 M = moles / 0.0077 L

0.00077 = moles

Solution B:

18.3 mL / 1,000 = 0.0183 L

Molarity = moles / volume

0.20 M = moles / 0.0183 L

0.00366 = moles

New Solution:

11.7 mL / 1,000 = 0.0117 L

New Volume = 0.0077 L + 0.0183 L + 0.0117 L

New Volume = 0.0377 L

New Moles = 0.00077 moles + 0.00366 moles

New Moles = 0.00443 moles

Molarity = moles / volume

Molarity = 0.0043 moles / 0.0377 L

Molarity = 0.1175 M = 0.12 M

Work arriving at total valence electrons are 24

The valence electron is an electron in the outer shell associated with an atom, and that can participate in the formation of a chemical bond

For a main-group element, a valence electron can exist only in the outermost electron shell; for a transition metal, a valence electron can also be in an inner shell.

Lewis structures, also known as Lewis dot formulas, Lewis dot structures, electron dot structures, or Lewis electron dot structures (LEDS), are diagrams that show the bonding between atoms of a molecule, as well as the lone pairs of electrons that may exist in the molecule.

Calculating the work arrival at total valence electrons

We know 1 bond contains

2 valence electrons

Here CCl4 contains 4 bonds that is 8 valence electrons

Therefore ,

Total valence electrons are 32

Now valence electrons remain after bond formation =

32 - 8

=24 valence electrons

A molecular model is a physical model of an atomistic system that represents molecules and their processes

Molecular image and lewis hand drawn structure is as shown below

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Answer:

64

Explanation:

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Answer:

Boron, Hydrogen, Helium, Lithium, Beryllium, Carbon, Nitrogen, Oxygen, etc.

Explanation:

These are all elements, not all of them.

The statement which is not true is as follows:

Thus, the correct option is C.

An equilibrium may be defined as the condition in which both the reactants and products are present in concentrations that have no additional propensity to alter with time so that there is no noticeable transformation in the possessions of the system.

The causation of repulsive force was thought to be made by the overlap of atomic orbitals and in between the electrons of diverse atoms, it matters a lot.

The equilibrium distance between nuclei of two covalently bonded atoms is called the bond length of that atom. It is the atomic separation at equilibrium.

Equilibrium occurs when the attractive and repulsive forces neglected the effect of each other in a specific state.

Therefore, it is well described above.

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Answer:

=6×10^7metre

Explanation:

By using formula,

F=GMm/d^2

Answer:

The fifth answer choice (NH3 + H2O = NH4+ + OH-)

Explanation:

An acid-base reaction occurs when an acid and base combine, and the acid, (which is H2O in this case) "donates" a proton, or an H+ to the base. In this reaction, H2O gave one of its H+ to NH3, to make NH4+ and OH-. NH4+ now has a positive charge because it gained a positive ion, while OH- now has a negative charge because it gained a negative ion.