Which is an example of a chemical change?
a.the separation of a mixture into its components
b.the separation of a compound into its elements
c.the separation of gases from liquids
d.the separation of air into oxygen, nitrogen, and other components?

The first ionization energy for lithium has been represented as:

[tex]\rm \bold{Li\;\rightarrow\;Li^+\;+\;e^-}[/tex]

Ionization energy can be described as the smallest amount of energy necessary to remove the most loosely attached electron from an isolated neutral gaseous atom.

The first ionization energy has been the amount of energy needed to remove the first electron from an atom's outermost energy level.

The second ionization energy is the amount of energy required to remove the second electron and produce a divalent cation.

Thus, for lithium, initial ionization energy is represented by the chemical equation;

[tex]\rm \bold{Li\;\rightarrow\;Li^+\;+\;e^-}[/tex]

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The first ionization energy for lithium (Li) is represented by the chemical equation Li(g) → Li+(g) + e−, and requires an energy of approximately +54.4 eV.

The first Ionization energy refers to the amount of energy required to remove an electron from a gaseous atom or ion. For lithium, which is an alkali metal with atomic number 3, the electron configuration is [He]2s¹. In the case of Lithium, the first ionization energy removes the outermost electron, resulting in a Lithium-ion (Li+) and an electron (e−). This is represented by the chemical equation: Li(g) → Li+(g) + e−. This process requires a particular amount of energy.

The energy required to ionize the electron of Lithium is approximately +54.4 eV (electron Volts).

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Reaction (1) is a formation reaction because it represents the formation of Fe2O3(s) from its constituent elements Fe(s) and O2(g) in their standard states.

A formation reaction is a chemical reaction in which one mole of a compound is formed from its constituent elements in their standard state under standard conditions of temperature and pressure (STP). The standard state of an element is its most stable physical state at STP.

In a formation reaction, the reactants are always the elements from which the compound is formed, and the product is always the compound itself. The enthalpy change of a formation reaction is known as the standard enthalpy of formation (ΔHf°) and is a measure of the heat absorbed or released during the formation of one mole of the compound.

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Final answer:

The given reaction forming iron (III) oxide from iron and oxygen is identified as a formation reaction, adhering to the definition by involving elemental components in their standard states.

Explanation:

The question asks which of the given reactions is a formation reaction. A formation reaction is one in which a single compound is formed from its constituent elements in their standard states.

From the provided options, the first reaction, 2 Fe(s) + 3 O2(g) → Fe2O3(s), is a formation reaction because iron (III) oxide, Fe2O3, is being formed from its elemental components (iron and oxygen) in their standard states (solid for iron and gas for oxygen).

We see that in 1 rock, there are 31 atoms of Argon and 1 atom of Potassium so the relative concentration of Potassium is:

1 / 32

or can be written as:

1 / 2^5

So this means that 5 half-lives have passed.

So the years are:

years passed = 5 * 1.25 billion years = 6.25 billion years

Answer:

1.3 billion years

Explanation:

Answer:

evaporation

Explanation:

Evaporation is the process where a liquid, in this case water, changes from its liquid state to a gaseous state. Liquid water becomes water vapor. Although lower air pressure helps promote evaporation, temperature is the primary factor.

The enthalpy of formation of liquid ethanol (C2H5OH) is represented by the chemical equation combining carbon (solid), hydrogen gas, and oxygen gas to form ethanol.

The enthalpy of formation of liquid ethanol (C2H5OH) can be represented by the balanced chemical equation showing its formation from its elements in their standard states.

The equation is as follows:

C(s) + 3H2(g) + 1/2O2(g) → C2H5OH(l)

The enthalpy change for this reaction is -277.6 kJ/mol, indicating that the formation of liquid ethanol from its elements is exothermic.

1. **Convert the mass of A to moles:**

  - [tex]\(29.5 \, \text{g}\)[/tex] of A is approximately [tex]\(1.88 \, \text{mol}\)[/tex].

2. **Convert the number of moles of A to the number of moles of B:**

  - [tex]\(1.88 \, \text{mol}\)[/tex] of A corresponds to approximately [tex]\(2.82 \, \text{mol}\)[/tex] of B.

3. **Convert the number of moles of B to the molecules of B:**

  - [tex]\(2.82 \, \text{mol}\)[/tex] of B is approximately [tex]\(1.70 \times 10^{24}\)[/tex] molecules.

**Convert the mass of A to moles:**

The first step is to convert the mass of substance A to moles using its molar mass. The formula for moles [tex](\(n\))[/tex] is given by the mass [tex](\(m\))[/tex] divided by the molar mass [tex](\(M\)):[/tex]

[tex]\[ n_A = \frac{m_A}{M_A} \][/tex]

Given that the mass of substance A [tex](\(m_A\))[/tex] is 29.5 g and its molar mass [tex](\(M_A\))[/tex] is 15.7 g/mol:

[tex]\[ n_A = \frac{29.5 \, \text{g}}{15.7 \, \text{g/mol}} \approx 1.88 \, \text{mol} \][/tex]

**Convert the number of moles of A to the number of moles of B:**

The reaction ratio states that 2 moles of A produce 3 moles of B. Therefore, if [tex]\(n_A\)[/tex] is 1.88 mol, the corresponding moles of B [tex](\(n_B\))[/tex] can be calculated using the ratio:

[tex]\[ n_B = \frac{3}{2} \times n_A \][/tex]

[tex]\[ n_B = \frac{3}{2} \times 1.88 \, \text{mol} \approx 2.82 \, \text{mol} \][/tex]

**Convert the number of moles of B to the molecules of B:**

To convert moles of B to molecules [tex](\(N_B\))[/tex], you use Avogadro's number [tex](\(6.022 \times 10^{23}\) mol\(^{-1}\)):[/tex]

[tex]\[ N_B = n_B \times N_A \][/tex]

[tex]\[ N_B = 2.82 \, \text{mol} \times (6.022 \times 10^{23} \, \text{mol}^{-1}) \approx 1.70 \times 10^{24} \, \text{molecules} \][/tex]

The question probable may be:

In a chemical reaction, exactly 2 mol of substance A react to produce exactly 3 mol of substance B.

How many molecules of substance B are produced when 29.5 g of substance A reacts? The molar mass of substance A is 15.7 g/mol.

Convert the mass of A to moles

Convert the number of moles of A to the number of moles of B

Convert the number of moles of B to the molecules of B

The answer is: oil.

Synfuel (synthetic fuel) is a liquid fuel, rarely gaseous fuel, made from syngas.

Syngas is a mixture of carbon monoxide (CO) and hydrogen (H₂).

Syngas goes to additional conversion process to become liquid fuel.

Some methods for manufacturing synthetic fuels are methanol (CH₃OH) to gasoline conversion and direct coal liquefaction.

the maximum electrical work that the cell can accomplish when 51.0 g of copper is plated out is approximately [tex]\( -167549 \, \text{J} \).[/tex]

To find the maximum electrical work that the cell can accomplish when 51.0 g of copper is plated out, we can use the relationship between electrical work ( w ) and the amount of substance involved in the redox reaction.

The electrical work ( w ) done by a cell operating under standard conditions is given by:

[tex]\[ w = -nFE \][/tex]

Where:

- ( n ) is the number of moles of electrons transferred in the balanced redox reaction.

- ( F ) is the Faraday constant [tex](\( 96485 \, \text{C/mol} \)).[/tex]

- ( E ) is the standard cell potential of the redox reaction (in volts).

First, we need to determine the number of moles of electrons transferred in the reaction. From the balanced redox reaction:

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

We see that 2 moles of electrons are transferred for every 1 mole of copper plated out.

Given that the molar mass of copper ([tex]\( \text{Cu} \))[/tex] is approximately [tex]\( 63.55 \, \text{g/mol} \)[/tex], we can calculate the number of moles of copper plated out:

[tex]\[ \text{Moles of Cu} = \frac{\text{Mass}}{\text{Molar mass}} = \frac{51.0 \, \text{g}}{63.55 \, \text{g/mol}} \][/tex]

[tex]\[ \text{Moles of Cu} \approx 0.802 \, \text{mol} \][/tex]

Since 2 moles of electrons are transferred for every 1 mole of copper plated out, the number of moles of electrons transferred (\( n \)) is twice the number of moles of copper plated out:

[tex]\[ n = 2 \times 0.802 \, \text{mol} \][/tex]

[tex]\[ n = 1.604 \, \text{mol} \][/tex]

Now, we can use the standard reduction potentials to find the standard cell potential (E ) for the reaction. From the standard reduction potentials table, we have:

[tex]\[ E^\circ_{\text{cell}} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}} \][/tex]

[tex]\[ E^\circ_{\text{cell}} = E^\circ_{\text{Cu}^{2+}/\text{Cu}} - E^\circ_{\text{Zn}^{2+}/\text{Zn}} \][/tex]

Given that [tex]\( E^\circ_{\text{Cu}^{2+}/\text{Cu}} = 0.34 \, \text{V} \) and \( E^\circ_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \, \text{V} \)[/tex], we have:

[tex]\[ E^\circ_{\text{cell}} = (0.34 \, \text{V}) - (-0.76 \, \text{V}) \][/tex]

[tex]\[ E^\circ_{\text{cell}} = 1.10 \, \text{V} \][/tex]

Now, we can calculate the maximum electrical work [tex](\( w \)):[/tex]

[tex]\[ w = -nFE \][/tex]

[tex]\[ w = -(1.604 \, \text{mol} \times 96485 \, \text{C/mol} \times 1.10 \, \text{V}) \][/tex]

[tex]\[ w \approx -1.604 \times 96485 \times 1.10 \, \text{J} \][/tex]

[tex]\[ w \approx -167548.6 \, \text{J} \][/tex]

[tex]\[ w \approx -167549 \, \text{J} \][/tex]

So, the maximum electrical work that the cell can accomplish when 51.0 g of copper is plated out is approximately [tex]\( -167549 \, \text{J} \).[/tex]

To prepare 100 mL of a 0.15 M NaOH solution, you will need approximately 0.60 g of NaOH.

To calculate the mass of NaOH needed to prepare a 0.15 M solution, we need to use the formula:

Mass (g) = Molarity (M) x Volume (L) x Molar Mass (g/mol)

In this case, the molarity is 0.15 M and the volume is 100 mL (or 0.1 L). The molar mass of NaOH is 22.990 + 15.999 + 1.008 = 39.997 g/mol.

Mass (g) = 0.15 M x 0.1 L x 39.997 g/mol = 0.5999 g, which can be rounded to 0.60 g.

The atom would have 20 neutrons.

Mass number = neutrons + protons

40 = neutrons + 20

neutrons = 40 – 20 = 20

Evaporation is an endothermic process that requires the absorption of heat to occur, typically resulting in a perceived cooling effect. However, it is not inherently a cooling or warming process, nor is it an exothermic process.

Evaporation is an endothermic process, meaning it requires an input of heat to occur. The heat energy is used to overcome intermolecular attractions, allowing matter to change from one physical state to another. This is why when you leave a swimming pool or when you sweat, you feel cool. The process of evaporation absorbs heat from your body.

However, it's important to note that evaporation is not always a cooling process. While evaporation takes heat from the source, it doesn't inherently reduce the temperature of the source, the perceived cooling is due to the loss of heat. Also, evaporation is not a warming process, or an exothermic process, as it doesn't produce heat. In fact, the reverse process of evaporation - condensation - is exothermic, releasing heat as matter changes state.

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Secondary colors can be created from a mixture of primary colors, namely red, blue, and yellow. This is part of the subtractive color process. In the additive color process that involves light, the primary colors are red, green, and blue.

Secondary colors can be created from a mixture of primary colors, which are red, blue, and yellow. When these primary colors are mixed in the right proportions, they can produce secondary colors. For example, mixing red and blue in equal proportions results in purple, a secondary color. Similarly, a mixture of blue and yellow generates green, while red and yellow produce orange. These are examples of the subtractive color process, often associated with pigment mixing.

The human eye perceives a mixture of all colors in sunlight as white light. This fact is related to the additive color process, primarily concerned with light. Specifically, in this process, red, green, and blue are treated as primary colors. Their combinations can yield secondary colors, and when combined at full intensity, they give white light.

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Answer:

Gravitational force will increase with greater mass

Final answer:

Reduction of D-gulose typically produces D-gulitol (sorbose alcohol), a sugar alcohol. This reaction is analogous to the reduction of D-glucose to sorbitol, involving conversion of the aldehyde group to an alcohol.

Explanation:

The student asked about the product formed by the reduction of D-gulose. D-Gulose, an aldose sugar, can undergo reduction to yield a sugar alcohol, similar to how D-glucose can be reduced to sorbitol. In the case of D-gulose, the reduction typically would produce D-gulitol, also known as sorbose alcohol.

The reducing sugar characteristic mentioned in reference to lactose is due to the presence of a free aldehyde group or an equivalent group in cyclic forms that can act as a reducing agent, for instance in Fehling's solution or Tollen's reagent reactions. This is relevant because the reduction of D-gulose would involve the conversion of its aldehyde group to an alcohol.

Answer:

350g dextrose

Explanation:

To calculate how many g of dextrose are in 500ml of solution we have to know the following:

When we talk about x% m/v (mass / volume) it means that there are x grams of solute in 100 ml of solution. Then 70% means that there is 70g of dextrose per 100ml of solution.

To solve this we can say that if in 100 ml there are 70g. How many grams are in 500 ml?

We apply the simple three rule and solve:

   100ml -----------> 70g dextrose

   500ml----------> X g dextrose

500ml x 70g / 100ml = X

                         350g = X

There are 350 grams of dextrose in 500 ml of the 70% dextrose solution.

A 70% solution of dextrose means that the solution contains 70 grams of dextrose per 100 milliliters of solution.

To calculate the grams of dextrose in 500 ml of this solution, we can set up a proportion:

(70 g / 100 ml) = (x g / 500 ml)

To solve for x, we can cross-multiply and then divide:

70 g * 500 ml = 100 ml * x g

35,000 g·ml = 100 ml * x g

Dividing both sides by 100 ml: 350 g = x g

Thus, there are 350 grams of dextrose in 500 ml of the 70% dextrose solution.

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