How long have people studied chemistry?
A. Since chemicals were discovered
B.Since fire was discovered
C.Since the atom was discovered
D.Since gravity was discovered

Answer:

Pb⁺²(aq) + CO₃⁻²(aq) →  PbCO₃ (s)

In net ionic equation we cancel the ions that have equal moles on both sides so  Na⁺¹ and NO₃⁻¹ have equal moles on both sides so we canceled them.

Explanation:

Net ionic equation:

In net ionic equation we only write the ions that are involved in reaction. If the system have same moles of ions in initial and final stages we cancel them as they have the same amount and are present in ionic form in the reaction medium. To formulate an ionic equation we just cancel the ions which have the same moles in initial and final stages.

Chemical equation:

Pb(NO₃)₂ (aq) + Na₂CO₃(aq) → PbCO₃ (s) + NaNO₃ (aq)

Balanced chemical equation:

In a balanced chemical equation we write the reactants and products in molecular form with number of moles.

Pb(NO₃)₂ (aq) + Na₂CO₃(aq) → PbCO₃ (s) + 2NaNO₃ (aq)

Ionic equation:

In ionic equation we write the equation in ionic form. It involves all the ions which will produce when we add any ionic compound in reaction medium.

Pb⁺² +2NO₃⁻¹ + CO₃⁻² + 2Na⁺¹  → PbCO3 (s) + 2NO₃⁻¹ (aq) + 2Na⁺¹ (aq)

Net ionic equation

In net ionic equation we cancel the ions that have equal moles on both sides. As we can see in the above ionic equation that Na⁺¹ and NO₃⁻¹ have equal moles on both sides so we canceled them.

Pb⁺²(aq) + CO₃⁻²(aq)  → PbCO₃ (s)

Answer:

D) A high [H+  ] and a low pH

Explanation:

edge 2021 :)

Answer:

A substance with a high pOH would likely have A high [H+] and a low pH

Explanation:

EDG2021

Answer:

True

Explanation:

The molecule CH20 contains two single bonds and one double bond.

Answer:

Approximately 206 grams.

Explanation:

How many moles of sulfuric acid [tex]\mathrm{H_2SO_4}[/tex] are there in this solution?

[tex]\text{Number of moles of solute} = \text{Concentration} \times \text{Volume}[/tex].

The unit for concentration "[tex]\mathrm{M}[/tex]" is equivalent to mole per liter. In other words, [tex]\rm 1\;M = 1\; mol\cdot L^{-1}[/tex]. For this solution, the concentration of [tex]\mathrm{H_2SO_4}[/tex] is [tex]\rm 0.420\;M = 0.420\; mol\cdot L^{-1}[/tex].

[tex]\begin{aligned}n(\mathrm{H_2SO_4}) &= c(\mathrm{H_2SO_4}) \cdot V\\&= \rm 0.420\;mol\cdot L^{-1}\times 5.00\; L \\&= \rm 2.10\; mol\end{aligned}[/tex].

What's the mass of that [tex]\rm 2.10\; mol[/tex] of [tex]\mathrm{H_2SO_4}[/tex]?

Start by finding the molar mass [tex]M[/tex] of [tex]\mathrm{H_2SO_4}[/tex].

Relative atomic mass data from a modern periodic table:

[tex]\displaystyle M(\mathrm{H_2SO_4}) = 2\times \underbrace{1.008}_{\mathrm{H}} + 1\times \underbrace{32.06}_{\mathrm{S}} + 4\times \underbrace{15.999}_{\mathrm{O}} = \rm 98.072\;g\cdot mol^{-1}[/tex].

[tex]\text{Mass} = \text{Quantity in moles} \times \text{Molar Mass}[/tex].

[tex]m = n \cdot M = \rm 2.10\; mol \times 98.072\;g\cdot mol^{-1} \approx 206\; g[/tex].

In other words, the chemist shall need approximately 206 grams of [tex]\mathrm{H_2SO_4}[/tex] to make this solution. As a side note, keep in mind that the 206 grams of [tex]\mathrm{H_2SO_4}[/tex] also take up considerable amount of space. Therefore it will take less than 5.00 L of water to make the 5.00 L solution.

Answer:

Decrease in temperature

Addition of catalyst (Fe)

Answer:

III only

Explanation:

The rate of a chemical reaction (when reactant particles are gases) is increased by the following factors

The only correct option from the question is III

A catalyst increases the rate of chemical reaction by reducing the activation energy of the reaction. Activation energy is the minimum amount of energy required for a reaction to occur. So, when the activation energy is lowered, the time required to complete a reaction reduces, hence the rate of reaction increases.

Answer:

Science is exploration and technology is application

Explanation:

Answer 5:

Option three is the true answer. Technology is the application of the knowledge gained by science.

The science gained knowledge through observations and experiments that are further utilized by Technology.

Explanation:

Science is the study of exploring the universe while technology uses the laws and principles to apply for the easiness of mankind. Technology proves that science is the truth and can be benefited to human for comfort. For example, wright brothers started to fly in the air in a balloon but afterward, technology is being used to make airplanes, missiles, and helicopters, etc. So we can assume that technology applies the knowledge gained through Science.

Answer:

(i) 0.05 mol/L; (ii) 5 g/L

Explanation:

We can use the dilution formula:

c1V1 = c2V2

Data:

c1 = 0.5 mol/L; V1 = 100 cm3

Added water = 900 cm3

Calculations:

(i) Moles per litre

V2 = 100 + 900 = 1000 cm^3 = 1 L

0.5 × 100 = c2 × 1000

          50 = c2 × 1000

          c2 = 0.05 mol/L

(ii) Grams per litre

c2 = 0.05 mol/L × (105.99 g/1 mol) = 5 g/L

Answer:

Benzene Hexachloride

Explanation:

BHC in benzene mean ''Benzene Hexachloride''.

As you can see, There are only two words and three letters. Even though it is one word, Hexa = H and Chloride = C

After converting the given mass of oxygen to moles, we use the ideal gas law to calculate the pressure of the gas. Inserting the given values (and the universal gas constant) into the equation, we find that the pressure of the gas will be approximately 0.596 atm.

To calculate the pressure of the contained oxygen gas, we use the ideal gas law which is expressed as PV = nRT. Here, P stands for pressure, V is volume, n is the number of moles, R is the gas constant and T is temperature.

First, we need to convert the mass of oxygen into moles. Oxygen (O2) has a molar mass of 32g/mol, therefore 1.0g of O2 is 1.0/32 = 0.03125 mol.

Next, we substitute these values into the ideal gas law. We use R = 0.0821 L·atm/K·mol as the gas constant, n = 0.03125 mol for the number of moles, V = 4.00 L for the volume, and T = 293 K for the temperature.

By rearranging the equation to solve for pressure, we find P = nRT/V = (0.03125 mol)(0.0821 L·atm/K·mol)(293 K) / 4.00 L = 0.596 atm. Therefore, the pressure of the 1.0g of O2 contained in a 4.00L container at 293 K would be approximately 0.596 atm.

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The pressure of 1.0g of O2 contained in a 4.00L container at 293 K can be computed using the ideal gas law and is approximately 0.596 atm.

To compute the pressure of 1.0g of O2 in a 4.00L container at 293 K, we can use the ideal gas law, PV = nRT. The number of moles (n) can be computed by dividing the weight of the oxygen (1.0 g) by its molar mass (32 g/mol). Therefore, n = 1.0 g / 32 g/mol = 0.03125 mol.

This value may be plugged into the gas law equation along with R, the ideal gas constant (0.0821 L·atm/K·mol), and T, the temperature in Kelvin (293 K). Through solving for P, we get P = nRT/V = (0.03125 mol)(0.0821 L·atm/K·mol)(293 K) / 4.00 L = 0.596 atm. Thus, the pressure of the oxygen gas at 293 K in the 4.00 L container is 0.596 atm.

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Answer:

false

Explanation:

A combustion reaction is a burning process that occurs in the presence of an oxidant and a fuel. It is usually an energy releasing procedure in which the temperature of the environment is greater than that of the reactants.

Not all combustion reactions are redox reactions

In a redox reaction, one specie is oxidized and the other becomes reduced simultaneously.

Redox reactions are usually facilitated by the transfer of electron. One specie loses electrons to be gained by another specie.

Certain atoms in a combustion reaction will have to change their oxidation state.

During combustion, during combustion reaction, there is no transfer of electrons between reactants . None of the molecules changes oxidation state. For example;

   CH₄   +   2O₂       →    CO₂  +    2H₂O

The algebraic sum of all oxidation number of all atoms in a neutral compound is zero.

In the reaction above, all the atoms in going from reactants to products have a net oxidation number of zero.

carbon on both sides is 0

oxygen is 0

Hydrogen is 0

So there is no transfer electrons

There are certain combustion reactions where there are no redox reactions taking place making the given statement false.

Combustion is defined as a high temperature exothermic reaction between a fuel which acts as a reductant and an oxidant which is usually atmospheric oxygen.It does not result in fire as the flame is visible only when substance which undergoes combustion vaporizes.

Activation energy must be overcome so that combustion is initiated.Solid fuels such as wood and coal initially undergo endothermal pyrolysis which results in gaseous fuels. It is widely used in industry and the application is based on concepts of chemistry, physics and mechanics.

It is a complex chemical process involving many steps which depend on properties of combustible material. It is a type of redox reaction.There are some combustion reactions where there are no redox reactions taking place ,thus the given statement is false.

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Answer:

In a chemical reaction, the atoms and molecules that interact with each other are called reactants. In a chemical reaction, the atoms and molecules produced by the reaction are called products.

Hope this helps.

Answer is A) reactants

They originally enter the chemical reaction and are changed by it, the products are a result of this procedure.

Answer:

Reactants

Explanation:

As the reaction occurs, the reactants (elements and compounds on the left) are transformed into products (elements and compounds on the right), meaning that they change during the reaction

Answer:

D

Explanation:

The general equation for this is

F = G*m1*m2/r^2

If the distance (r) remains the same and m1 and m2 are both doubled, then the equation becomes

F1 = G * (2m1)(2m2)/r^2

F1 = 4 [G * m1 * m2)/r^2 ]

So F1 is 4 times as large as the initial Force (F)

Answer: D

When the mass of each object is doubled, the gravitational force between them becomes four times greater. Originally it is 100 N, so when each mass is doubled, the new gravitational force will be 400 N, according to Newton's law of universal gravitation.

The question is related to the gravitational force between two objects, which is directly governed by Newton's law of universal gravitation. This law states that the gravitational force (F) between two objects is directly proportional to the product of their masses (m1 and m2) and inversely proportional to the square of the distance (r) between their centers:

F = G × (m1 × m2) / r²

where G is the gravitational constant. If we double the mass of each object, the new force (F') will be:

F' = G × (2m1 × 2m2) / r² = 4 × (G × m1 × m2) / r² = 4F

Thus, the new gravitational force if the mass of each object is doubled will be four times the original force. Since the original force is given as 100 N, the new force will be:

F' = 4 × 100 N = 400 N

Therefore, the correct answer is:

d: 400 N

1 mole = 6.022*10^23 atoms

So, we divide 5.22*10^22 by 6.022*10^23

Answer is 8.67*10^-2

Mole is described as the amount of the substance containing the identical wide variety of discrete entities (atoms, molecules, ions, and so forth) as there are atoms in a sample of pure 12C weighing precisely 12g. The quantity of debris present in one mole of any substance =Avogadro Number=6.

Avogadro's number is a single mole of any substance (described as its molecular weight in grams), the same as 6.02214076 × 1023.

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Answer: A) Reduces friction between soil grains

Hope this helps!!! :)

Explanation:

Groups contain more than 1 and a period doesn't last long unlike a group where it last for a quite some time

The higher into the atmosphere you go, the cooler it becomes. This is because at higher elevations there is a lower air density that allows infrared bouncing from the earth surface to escape to space – because they collide with fewer air molecules than in the lower atmosphere.  

Higher elevated areas- like mountainous regions-  are also more likely to receive rainfall than low elevated areas.   This is because they force warm moist air into the cooler upper atmosphere where the moisture condenses and precipitates.

Final answer:

Latitude affects temperature as regions closer to the equator receive more solar energy, resulting in higher temperatures. At higher latitudes, the angle of the sun's rays decreases, leading to cooler climates. These temperature differences drive circulation patterns that influence precipitation, with deserts often forming at around 30° latitude due to dry descending air.

Explanation:

How Latitude and the Sun's Rays Affect Temperature and Precipitation

Temperature and precipitation patterns are greatly influenced by a region's latitude and the angle at which the sun's rays hit the Earth. Near the equator, where latitude is low, the sun's rays are more direct, leading to higher temperatures and often higher levels of precipitation due to rapid evaporation and condensation. As we move towards higher latitudes, the angle of the sun's rays becomes more oblique, resulting in less solar energy and cooler temperatures.

Climate and Latitude

Regions located at or near the equator, known as the tropics, experience higher temperatures because they receive more solar energy than regions at higher latitudes. On the other hand, areas at the poles receive minimal solar energy due to the very oblique angle of the sun's rays, contributing to much colder climates. This uneven heating is primarily responsible for the large-scale circulation patterns in the atmosphere, which in turn affect precipitation levels.

Precipitation Patterns

Deserts typically form at around 30° latitude due to descending air that inhibits cloud formation, leading to arid conditions. Additionally, global air currents and the presence of mountains can create rain shadows, further affecting local precipitation.

Answer:

The following reaction shows the production of hydrogen gas from water. This chemical reaction should be classified as decomposition ( second choice)

Answer:

B. Decomposition

Explanation:

[tex]2 H_2 O>2H_2+O_2[/tex]

Decomposition is the type of reaction in which a compound is broken into smaller  compounds or broken into its elements

[tex]AB>A+B\\\\CaCO_3>CaO+CO_2[/tex]

Synthesis is just opposite to decomposition reaction, Elements combine to form a compound

[tex]A+B>AB\\\\CaO+CO_2>CaCO_3[/tex]

Single replacement reactions in which replacement takes place at a single place

[tex]A+BC>AB+C\\\\Zn(s)+CuCl_2 (aq)>ZnCl_2 (aq)+Cu(s)[/tex]

Double replacement reactions in which replacement occurs two places

[tex]AB+CD>AD+BC\\\\AgNO_3+NaCl>AgCl+NaNO_3[/tex]

Neutralization reaction is the reaction between an acid and a base to form salt and water

[tex]HCl+NaOH>NaCl+H_2 O[/tex]

Answer:

B

Explanation:

The oxidation state is present in metals that have multiple oxidation states. Most transition metals have multiple oxidation states. Such as, Iron(II) and Iron (III).

Answer:

When the metal can exist in more than one oxidation state

Explanation:

When metal exhibit more than one oxidation sate, we have to write the oxidation number of the metal in front of it to for a better clarity.

Most of the transition metals exhibit more than one oxidation state due to presence of d electrons.

For example  the oxidation state of iron are "+2 and +3"

The oxidation state of copper are "+1 and +2"

The oxidation state of Mn are :"+2", +4, +7.

so we generally write there oxidation state in roman

For Mn compound in +2 oxidation state we write Mn(II)

For Mn compound in +7 oxidation state we write Mn(VII)

Answer: Option (C) is the correct answer.

Explanation:

Matter is defined as a substance which has mass and occupies volume. The three states of matter are solid, liquid and gas.

Elements which are present in group 17 are known as halogens.

Elements present in this group are fluorine, chlorine, bromine and iodine.

At room temperature, both fluorine and chlorine exists as a gas.

Bromine exists as a liquid and iodine exists as a solid.

Therefore, we can conclude that halogen groups are likely to have elements in three states of matter.

It is not necessarily that compound of hydrogen and has been acidic in nature.

The hydrogen in a compound has been the determination of the  sharing and transfer of the electrons between hydrogen and other element.

The acidic compound has been responsible for the hydrogen ion in the solution. The compounds that have been comprising hydrogen are not necessarily to be acidic in nature.

For example, methane has  been the compound of hydrogen and carbon. It has been a compound of hydrogen and has not been acidic in nature.

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Answer:

change of state

Explanation:

chemical change is a permanent change

The choices that best indicate that a substance has experienced a chemical change are

1. When the substance changes temperature

2. when the substance changes shape

4. when a new substance is formed

A chemical change is a change that happens after a chemical reaction. These changes are changes in the shape, structure, or pH of the substance.

When two substances join together to form a new compound or substance. Then it is a chemical change. The volume will not change in the chemical change because the volume the reactant has will be the same as the product.

The temperature change is a chemical change and when the substance changes its shape. It is a chemical change when wood burns and changes into coal or ash.

Thus, the correct options are  1, 2, and 4.

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The question is incomplete. Your most probably complete question is given below:

Select all that apply.

Answer:

A

Explanation:

The last one (D) describes an endothermic reaction. D is not right.

The total energy will not increase. If it did everyone would use that reaction in their automobiles. That's getting something for nothing. B is not right.

C is wrong as well. If anything, the reaction will try to get rid of Thermal Energy. That means

A is correct. A is the exact opposite to C.

Answer:

I believe it's HF

Explanation:

Answer:  A. HF    Explanation:(Ka for HF is 7.2X10^-4)

Answer: I think that the answer is Z.

Answer:

3.89 kg P2O5 must be used to supply 1.69 kg Phosphorus to the soil.

Explanation:

The molecular mass of P2O5 is

P2 = 2* 31 =           62

O5 = 5 * 16 =         80

Molecular Mass = 142

Set up a Proportion

142 grams P2O5 supplies 62 grams of phosphorus

x    kg P2O5        supplies 1.69 kg of phosphorus

Though this might be a bit anti intuitive, you don't have to convert the units for this question. The ratio is all that is important.

142/x = 62/1.69            Cross multiply

142 * 1.69 = 62x           combine the left

239.98 = 62x               Divide by 62

239.98/62 = x

3.89 kg of P2O5 must be used.

Decomposition is a reaction in which a compound is broken down into its components. The mass of pure P2O5 is obtained by mass- mole relationship.

The equation of the decomposition of P2O5  is;

[tex]2 P2O5 -----> P4 + 5 O2[/tex]

Number of moles phosphorus supplied to the soil = [tex]\frac{1.69 * 10^3}{124 g/mol}[/tex] = 13.6 moles

From the reaction equation, we can see that;

2 moles  P2O5 yields 1 mole of phosphorus

x moles of  P2O5 yields 13.6 moles of phosphorus

x = 2 mole * 13.6 moles/ 1 mole

x = 27.2 moles

Mass of  pure P2O5 = 27.2 moles * 142 g/moles = 3862 g or 3.862 Kg

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Hey there!:

Option B,CO2 at 353K

*Since most collisions means that highest kinetic energy.

*As we know that kinetic energy of gas molecules is directly proportional to absolute temperature

*More the temperature, More the kinetic energy.

* Hence B  is the correct answer as it has highest temperature.

Hope this helps!

Answer: Option (b) is the correct answer.

Explanation:

As it is known that more is the kinetic energy present between the molecules of a gas, more will be the number of collisions take place.

Also, relation between kinetic energy and temperature is as follows.

                     K.E = [tex]\frac{3}{2}kT[/tex]

This means that more is the temperature of gas more will be the kinetic energy present withing its molecules or vice-versa.

As methane is at 340 K.

Carbon dioxide is at 80 [tex]^{o}C[/tex] = (80 +273) K = 353 K

Argon is at 265 K and helium is at 20[tex]^{o}C[/tex] = (20 + 273)K = 293 K

Therefore, temperature of carbon dioxide gas is the maximum.

Thus, we can conclude that the carbon dioxide gas at 80[tex]^{o}C[/tex] will have the most collisions between its particles.

Answer:

B. 387 V

Explanation:

Ohm's law states that the voltage is the product of the current and resistance.

V = IR

V = (9 A) (43 Ω)

V = 387 V

Answer:

A. Hydrogen and helium

Explanation:

Hydrogen and helium escaped the earth's early atmosphere. A cloud of gases surrounded the early earth that primarily had no magnetic field and gravity to trap some of the gases.

This was why these light weight gases were able to escape the early earth's atmosphere and we don't have them today.

Answer:

In a voltaic cell, the Anode Loses electrons and is oxidized, while the Cathode Gains electrons and is reduced.

Explanation:

The strongest reducing agent which is the Anode is oxidized, the Anode is negative so it loses electrons.

The strongest oxidizing agent is the Cathode, which is positive so it gains.

Also for further confirmation, I got it right on the test.

In a voltaic cell, the anode loses electrons and is oxidized, while the cathode gains electrons and is reduced. The voltaic cell operates on a redox reaction, generating current as a result of electron transfer from the anode to the cathode, driven by a potential difference or voltage.

In a voltaic cell, the anode loses electrons and is oxidized, while the cathode gains electrons and is reduced.

Understanding Voltaic Cells

A voltaic cell is an electrochemical cell that uses a spontaneous redox reaction to produce electrical energy. It is constructed from two half-cells connected by a conductive wire and a salt bridge. Each half-cell contains an electrode immersed in an electrolyte. The anode is where the oxidation reaction, or loss of electrons, takes place, making it the negative electrode. Conversely, the cathode is where the reduction reaction, or gain of electrons, occurs; thus, it is the positive electrode. The flow of electrons from the anode to the cathode through the wire generates electrical current.

The potential difference, or voltage of the cell, is determined by the difference in reduction potentials of the two half-reactions. The electrode with the higher reduction potential becomes the cathode, where reduction takes place, and the one with lower reduction potential becomes the anode, where oxidation occurs.

Understanding the functions of the anode and cathode is essential in analyzing and constructing voltaic cells, which can be used to power various electrical devices.

Answer:

The products are beyond the "yield" symbol [→] to the right.

I am joyous to help.