How much energy is required to melt 2 kg of copper? Use the table below and
this equation: Q = ml fusion
A. 9460kJ
B. 414kJ
C. 4730kJ
D. 125.6kJ

The variable that is unknown until the experiment is performed is the dependent variable.

In a scientific experiment, variables are classified into two main categories: independent variables and dependent variables. The independent variable is the variable that is intentionally manipulated or changed by the experimenter. It is under the control of the experimenter and is deliberately altered to observe its effect on the dependent variable.

On the other hand, the dependent variable is the variable that is measured or observed as the outcome or response in the experiment. It is the variable that is expected to change in response to the manipulation of the independent variable. The value or behavior of the dependent variable depends on the value or behavior of the independent variable.

Typically, before conducting an experiment, researchers have a hypothesis or an expectation about how the independent variable will affect the dependent variable. However, the actual outcome or result of the experiment, which is observed through the measurement of the dependent variable, remains unknown until the experiment is performed.

The purpose of conducting the experiment is to gather empirical data and observe the changes in the dependent variable to analyze the relationship between the independent and dependent variables.

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By understanding conversion factors and how they are related to each other we can use dimensional analysis to solve  problems.

Dimensional Analysis is a step by step approach to solving problems in Physics, Chemistry , and Mathematics. It involves having a clear knowledge and understanding to be able to convert a given unit to another in the same dimension using  conversion factors and knowing how they are related to each other.

For instance, In Chemistry, we want to Convert 120mL to L.(note that ml stands for millilitres and ;L stands for litres)

Or first approach will be to write out the conversion factor related to our problem which is

1000ml =1L

such that 120ml = (we cross multiply))

giving us  120ml x 1L/1000ml =0.12L

This same process is applied to convert any type of dimensional analysis problems be it physics or mathematics.

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Answer:

C

Explanation:

All of the other options fall under either history or subjective opinion, and C is the only one which refers the actual properties of the planet itself.

Answer:

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

\(n = \frac{N}{L} \\ \)

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

\(n = \frac{4.23 \times {10}^{25} }{6.02 \times {10}^{23} } \\ = 70.265780...\)

We have the final answer as

Hope this helps you

Answer:

Explanation:

Balance the reaction of Al + HCl = AlCl3 + H2 using this chemical equation balancer!

Answer:

molecular weight of NH3 or grams This compound is also known as Ammonia. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles NH3, or 17.03052 grams.

No. of moles present in 12 grams of NH₃ are 0.705 moles.

Avogadro's number is the number of units in one mole of any substance and equals to 6.02214076 × 10²³. The units can be electrons, atoms, ions, or molecules.

No. of moles is defined as a particular no. of particles that we can calculate with the help of Avogadro’s number.

Given,

Mass of NH₃ = 12g

one mole of any substance = 6.02214076 × 10²³

Molar mass NH₃ = 17g

17g NH₃ has = 1 mole

1g NH₃ has = (1÷17) moles

12g NH₃ has = 0.058 × 12 moles = 0.705 moles

Therefore, No. of moles present in 12 grams of NH₃ are 0.705 moles.

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Answer:

oxygen, carbondioxide

carbondioxide, oxygen

Answer:

C

Explanation:

electronic waves transmits energy but mechanical waves require a medium in order to transport their energy from bgg one place to another.

Answer:

it is B.) Electromagnetic waves vibrate in two directions that are

Explanation:

stay safe 2021

Answer:

The answer is A.

Explanation:

They are both made of amino acids.

3. (a) Ni electrode can serve as the standard electrode as its reduction potential is zero. It can act a reference standard electrode as the species with reduction potential values more positive to it will get reduced and species with reduction potential values more negative to it will get oxidized. Thus Ni electrode can serve as reference standard electrode.

(b) Cu2+ ion is most easily reduced as it has positive reduction value thus it act as good oxidizing agent by oxidizing other an itself get reduced.

(c) Al metal is most easily oxidized as it has most negative reduction potential value thus it act as good reducing agent by reducing others and itself get oxidized.

(d) Copper and aluminium electrodes are connected to battery to form a spontaneous cell

(i) Al is oxidized as it has negative reduction potential value, thus it loses 3 electrons and form Al3+ ion.

(ii) Al metal act as anode. Because at anode always oxidation takes place. So Al is oxidized to Al3+ at anode.

(iii) At anode: 2 Al (s) 1  2 Al3+ (aq) + 6e-

At cathode: 3 Cu2+ (aq) + 6e- 1  3 Cu (s)  

Net ionic equation: 2 Al (s) +  3 Cu2+ (aq) 1  2 Al3+ (aq) + 3 Cu (s) 

(iv) E0cell = E0cathode - E0anode 

E0cathode = E0Cu2+/ Cu  = 0.62 V                

E0anode = E0Al3+ / Al = -1.38 V

E0cell  = 0.62 V - (-1.38) V = 2 V

As the standard electrode potential of cell is positive, thus the cell reaction is spontanoeus and will proceed in forward direction.

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In halite (NaCl), the bond present is an ionic bond.

Ionic bonds form between atoms with significantly different electronegativities. Sodium (Na) has a low electronegativity, while chlorine (Cl) has a high electronegativity. In the formation of halite, sodium loses an electron to chlorine, resulting in the formation of positively charged sodium ions (Na+) and negatively charged chloride ions (Cl-).

The ionic bond is the electrostatic attraction between these oppositely charged ions. The positive sodium ions are attracted to the negative chloride ions, creating a strong bond that holds the crystal lattice structure of halite together.

Ionic bonds are characterized by the transfer of electrons between atoms, resulting in the formation of ions. They are typically found between metals and nonmetals, where the metal atom loses electrons to the nonmetal atom.

In the case of halite (NaCl), the bond is formed between the metal sodium (Na) and the nonmetal chlorine (Cl), making it an ionic bond.

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To combine ions to form ionic compounds, we need the combine in such a way that it gets neutral charge.

We can combine each anion with each cation to get the 4 compounds we need.

To combine SO₄²⁻ with Pb⁴⁺ we first find the Least Common Multiple of their charges, 2 and 4.

They have the factor 2 in common, so the LCM is 4. This is the final charge of each that will cancel out.

To get 4+, we only need 1 Pb⁴⁺.

To get 4-, we need 2 SO₄²⁻.

So, the formula is:

Pb(SO₄)₂

To combine SO₄²⁻ with NH₄⁺ is easier because one of them has single charge. In this case, we can simply pick one of the multiple charge ion and the same amount that will cancel its charge of the single charged one.

So, we picke 1 SO₄²⁻, ending with 2-.

And we picke 2 NH₄⁺, ending with 2+.

The formula:

(NH₄)₂SO₄

To combine C₂H₃O₂⁻ with Pb⁴⁺ we do the same, because the anion is single charged.

Pick 1 Pb⁴⁺, ending with 4+.

Pick 4 C₂H₃O₂⁻, ending with 4-.

The formula:

Pb(C₂H₃O₂)₄

To combine C₂H₃O₂⁻ with NH₄⁺, both have same charge, so we just need one of each and their charges will cancel out.

The formula:

NH₄C₂H₃O₂

So, the formulas are:

Pb(SO₄)₂

(NH₄)₂SO₄

Pb(C₂H₃O₂)₄

NH₄C₂H₃O₂

The pressure will increase if the gas is changed from nitrogen to helium.

The question is incomplete but I will try to help the much I can. We must note that the kinetic energy of the molecules of a gas depends on the temperature and the molar mass of the gas.

Since the average velocity of a gas depends on molar mass also, the pressure will increase if the gas is changed from nitrogen to helium.

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The molar mass of a substance is given by the ratio of given mass will number of moles and here the molar mass of the protein is 47,937.71g/mol.

Formula used:- πππππ= MRT (where, pi = osmatic pressure, M= Molarity and T= temperature).

Given that:- pi= 0.059atm.

T=27°C= 300K.

R= 0.0821 Latm\(K^{-1} mol^{-1}\).

\(M= \frac{24}{molar mass} * \frac{1}{0.209L}\).

Molar mass= \(\frac{24g}{0.209L} *\frac{300K}{0.059} *0.0821= 47,937.71g/mol.\)

therefore, the molar mass of the protein is 47,937.71g/mol.

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Answer: the volume increases

Explanation: It increasses because the volume is how tall it is

At 10°C :

Temperature (in Kelvin) :

\(\qquad \tt \dashrightarrow \: 10 + 273\)

\(\qquad \tt \dashrightarrow \: 283 \: k\)

Now,

Temperature in Kelvin (at 150° C)

\(\qquad \tt \dashrightarrow \:150 + 173\)

\(\qquad \tt \dashrightarrow \:323 \: k\)

Now, let's find the volume (x) [ assume pressure to be constant ]

\(\qquad \tt \dashrightarrow \: \dfrac{V_1}{T_1} = \dfrac{V_2}{T_2}\)

\(\qquad \tt \dashrightarrow \: \dfrac{3.8}{283} = \dfrac{x}{323}\)

\(\qquad \tt \dashrightarrow \: \dfrac{3.8}{283} \times 323 = {x}\)

\(\qquad \tt \dashrightarrow \: {x} \approx4.34 \: \: litres\)

Answer:

1. Hot air rises and cold air descends for exactly the same reason

Matter are anything that is made up of atoms. The quantity of matter can be seen only on the basis of mass and volume calculation. Therefore, warm air rise and cold air sink.

Matter is a substance that has some mass and can occupy some volume. The matter is mainly used in science.

Matter is anything that is made up of atoms. Mass can also be represented as number of molecules. We also saw that matter occupy some volume and that volume is measured only in liter.

Warm air rises while cold air descends. This is because hotter air takes more energy than cooler air. Furthermore, hot and cold temperatures are precisely proportionate to their density. As a result, when it's really hot, the hotter air is more likely to rise than when it's very cold.

Therefore, warm air rise and cold air sink.

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Answer:

The formation of a gas is a clue to chemical changes. The bubbles of gas that you observed form when an antacid is dropped into water is an example of change. Another clue that a chemical change has occurred is the formation of a solid.

Explanation:

The ligand that produces the strongest crystal field is the ligand with the highest charge and smallest size.

In coordination chemistry, ligands are molecules or ions that donate electron pairs to a central metal ion. When ligands bind to a metal ion, they create a crystal field, which is the electrostatic field generated by the charged ligands around the central metal ion.

The strength of the crystal field depends on the properties of the ligands.

Two main factors that influence the strength of the crystal field are the charge and size of the ligands. Ligands with higher charges or multiple negative charges create stronger crystal fields because they exert a greater electrostatic force on the central metal ion. Additionally, ligands with smaller sizes can approach the metal ion more closely, leading to stronger interactions.

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Answer:

True.

Explanation:

According to this, an object's rate of change in velocity is directly proportional to the force used and moves in the direction of the applied force. The following formula encapsulates it: force (N) = mass (kg) x acceleration (m/s2). A constant mass item will therefore accelerate in direct proportion to the force exerted.

Answer:

true, I am pretty sure it's true

Answer:

Imagewww.chem.purdue.edu › Equilibrium

Calculating the Hydroxide Ion Concentration from pOH

To calculate the pH of an aqueous solution you need to know the concentration of the hydronium ion in moles per liter ...

Calculating pH

Calculating hydronium ion ...

Calculating pOH

Calculating hydroxide ion ...

Calculating pKa

People also ask

How do you find hydronium ion concentration when given pH?

The hydronium ion concentration can be found from the pH by the reverse of the mathematical operation employed to find the pH. [H3O+] = 10-pH or [H3O+] = antilog (- pH) Example: What is the hydronium ion concentration in a solution that has a pH of 8.34? On a calculator, calculate 10-8.34, or "inverse" log ( - 8.34).

Answer:

False

Explanation:

Answer:

false

Explanation:

pressure has nothing to do with the phases of a substance.

The energy of one mole of CO₂ increased when it absorbs infrared radiation with a wavenumber of 2400 cm⁻¹ is 2.869 × 10³ J/mol.

The energy of one mole of CO₂ increased when it absorbs infrared radiation with a wavenumber of 2400 cm-1 can be calculated using the equation E = hcν.

Where,
E = energy
h = Planck's constant (6.626 × 10⁻³⁴ J s)
c = speed of light (2.998 × 10⁸ m/s)
ν = wavenumber (2400 cm⁻¹ or 2.4 × 10⁴ m⁻¹)

Plugging in the values, we get:
E = (6.626 × 10⁻³⁴ J s) × (2.998 × 10⁸ m/s) × (2.4 × 10⁴ m⁻¹)
E = 4.763 × 10⁻²¹ J

Since the question asks for the energy of one mole of CO2, we need to multiply the energy of one molecule by Avogadro's number (6.022 × 10²³ mol⁻¹):
E = (4.763 × 10⁻²¹ J) × (6.022 × 10²³ mol⁻¹)
E = 2.869 × 10³ J/mol

Therefore, the energy of one mole of CO₂ is 2.869 × 10³ J/mol.

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The process that separates pigments from a plant extract is known as chromatography.

This technique involves the separation of different components of a mixture based on their chemical properties and interactions with a stationary phase and a mobile phase. In the case of plant pigments, the stationary phase can be a paper or a thin layer of silica gel or alumina, and the mobile phase is typically a solvent that is able to dissolve the pigments.
When the plant extract is applied to the stationary phase, the pigments will migrate through the mobile phase at different rates depending on their chemical properties, such as their polarity and size. This results in the separation of the pigments into distinct bands or spots on the stationary phase.
There are several types of chromatography techniques that can be used to separate pigments from a plant extract, including paper chromatography, thin-layer chromatography, and high-performance liquid chromatography. These techniques vary in their level of sensitivity, resolution, and speed, but they all rely on the principles of chromatography to isolate and identify the different pigments present in the plant extract.

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Answer:

1 d

2 c

3 b

4 e

5 a

Lithium permanganate has a percent composition of 3.99% Lithium, 31.61% Magnesium, and 46.22% for each element.

If we know the molar mass of each element and the molecular formula of the molecule, we may compute the composition of the elements. Hence, 18.78% of lithium is present in lithium carbonate by mass. Recall that a compound's overall percentage composition of all the elements is always 100%.

To calculate the percentage, we must first divide the amount by the total value and then multiply the result by 100.

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The approximate distance from the far edge of one lobe to the far edge of the other is 2,100,000 light-years.

This distance measures the outer space between the edges of the two lobes in a given time.

The approximate distance from the far edge of one lobe to the far edge of the other in a solar system is about 2,100,000 light-years.

Thus, the approximate distance from the far edge of one lobe to the far edge of the other is 2,100,000 light-years.

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Answer:

Both b/c a chemical formula tells you how many and a sketch formula shows how they are bonded together.

Molecular formulas show how many atoms of each element one molecule of a compound contains. Note: Ionic compounds are generally crystalline solids with high melting points. Other compounds, however, have very different properties.

The sketch of the molecule like in the structural formula provides more information than the chemical formula of the molecule.

A structural formula can be described as a representation of a molecule that involves the arrangement of atoms and chemical bonds of a molecule. The structural formulas contain elemental symbols that represent the atoms that are connected by lines that represent the chemical bonds.

One line depicted a single covalent bond, whereas two and three lines represent double and triple bonds respectively. Molecular formulas can be described as a representation of the number of atoms of each element in a molecule.

For example, the molecular formula for water is H₂O and the molecular formula of isopentane is C₅H₁₀.

Molecular formulas do not show how the atoms of the elements are bonded together. Structural formulas represent that how exactly each atom is bonded to another atom. Therefore, the Structural formula provides more information about molecule.

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The substance in the image above would be classified as a mixture of elements (option E).

A compound is a substance formed by chemical bonding of two or more elements in definite proportions by weight.

On the other hand, a mixture is made when two or more substances are combined, but they are not combined chemically.

According to this question, an image is shown with two different substances or elements as distinguished by coloration (white and purple). These elements are combined but not chemically bonded, hence, is a mixture.

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a) The Lennard-Jones potential predicts the separation r_eq at the minimum energy U_min.

b) The U_min for this interaction at T=298 K is the value obtained from the Lennard-Jones potential equation when r=r_eq.

c) The ratio of U_min to the purely attractive van der Waals component of the interaction potential at r_eq can be calculated by comparing the attractive part (-A/r^6) to the total potential energy U_min.

d) The ratio of r_eq to r_0, where u(r_0)=0.4, can be determined by finding the value of r_eq where the potential energy is equal to 0.4 times the total potential energy at r=r_0.

e) The ratio of r_s to r_0, where r_s is the separation where the magnitude of the attractive adhesion force is maximum, can be determined by finding the value of r where the derivative of the potential energy with respect to r is equal to zero.

f) The value of F_max between the two atoms can be obtained by taking the negative derivative of the potential energy equation with respect to r and evaluating it at r=r_s.

a) The Lennard-Jones potential provides information about the relationship between energy and separation between two interacting atoms.

At the minimum energy (U_min), the potential predicts the separation r_eq, which corresponds to the equilibrium distance between the atoms. This is the distance at which the energy of the system is at its lowest point.

b) To determine the value of U_min at a given temperature (T=298 K), you can substitute the equilibrium separation r_eq into the Lennard-Jones potential equation and calculate the resulting energy value.

This will give you the U_min for the interaction.

c) The Lennard-Jones potential consists of two components: an attractive component (-A/r^6) and a repulsive component (B/r^12).

The ratio of U_min to the purely attractive van der Waals component of the interaction potential at r_eq can be calculated by comparing the magnitude of the attractive component to the total potential energy at the equilibrium separation.

This ratio provides insights into the relative contribution of the attractive force to the overall potential energy at equilibrium.

d) The ratio of r_eq to r_0 can be determined by finding the value of r_eq where the potential energy is equal to 0.4 times the total potential energy at r=r_0.

In other words, you need to solve the Lennard-Jones potential equation for r_eq when the potential energy is equal to 0.4 times the potential energy at r=r_0.

e) The ratio of r_s to r_0 is obtained by finding the value of r where the magnitude of the attractive adhesion force is maximum.

This can be determined by finding the separation r where the derivative of the potential energy equation with respect to r is equal to zero.

The value of r_s represents the separation at which the attractive force between the atoms is strongest.

f) The value of F_max between the two atoms can be obtained by taking the negative derivative of the Lennard-Jones potential energy equation with respect to r and evaluating it at r=r_s.

This will give you the magnitude of the maximum attractive adhesion force between the atoms.

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