A rock contains one-fourth of its original amount of potassium-40. The half life of potasium-40 is 1. 3 billion years. Calculate the rock´s age

The equilibrium constant, Kc, is 2.93 x 10^-4.

The balanced equation for the reaction is;

NH₃ (g) ⇌ ½ N₂ (g) + 3/2 H₂ (g)

The equilibrium expression for the reaction is;

Kc = ([N₂\(]^{(1/2)}\) [H₂\(]^{(3/2)}\)) / [NH₃]

We are given the initial and equilibrium concentrations of NH₃. The change in NH₃ concentration is;

Δ[NH₃] = [NH₃]equilibrium - [NH₃]initial = 7.91 g/L - 15 g/L = -7.09 g/L

Since NH₃ is a reactant, its concentration decreases at equilibrium. Therefore, we can assume that the reaction proceeds in the forward direction, and that the concentration of N₂ and H₂ at equilibrium are both equal to x.

Using the ideal gas law, we can find the concentration of NH3 at equilibrium; PV = nRT

n/V = P/RT

[n(NH₃)]equilibrium = (P/RT) x V

[n(NH₃)]initial = (P/RT) x V

Substituting the values, we get;

[n(NH₃)]equilibrium = (1 atm / (0.0821 L·atm/mol·K x 298 K)) x 1.4 L = 0.0652 mol/L

[n(NH₃)]initial = (1 atm / (0.0821 L·atm/mol·K x 298 K)) x 1.4 L = 0.0652 mol/L

Using the balanced equation, we can relate the concentration of NH3 to the concentrations of N₂ and H₂.

[NH₃]initial = 0.0652 mol/L

[N₂]equilibrium = [H₂]equilibrium = x

[N₂]initial = [H₂]initial = 0 mol/L

Substituting into the equilibrium expression, we get;

Kc = ([N₂\(]^{(1/2)}\) [H₂\(]^{(3/2)}\)) / [NH₃]

Kc = (\(X^{(1/2)}\) \(X^{(3/2)}\)) / (0.0652 - 7.09x10⁻³)

Kc = 2.93 x 10⁻⁴

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Answer:

The less valence electrons an atom has, the least likely it will gain electrons. Electron affinity decreases down the groups and from right to left across the periods on the periodic table because the electrons are placed in a higher energy level far

Explanation:

Answer:

Electron affinity increases upward for the groups and from left to right across periods of a periodic table because the electrons added to energy levels become closer to the nucleus, thus a stronger attraction between the nucleus and its electrons. Remember that greater the distance, the less of an attraction; thus, less energy is released when an electron is added to the outside orbital. In addition, the more valence electrons an element has, the more likely it is to gain electrons to form a stable octet. The less valence electrons an atom has, the least likely it will gain electrons.

Electron affinity decreases down the groups and from right to left across the periods on the periodic table because the electrons are placed in a higher energy level far from the nucleus, thus a decrease from its pull. However, one might think that since the number of valence electrons increase going down the group, the element should be more stable and have higher electron affinity. One fails to account for the shielding affect. As one goes down the period, the shielding effect increases, thus repulsion occurs between the electrons. This is why the attraction between the electron and the nucleus decreases as one goes down the group in the periodic table. hope i helped

Explanation:

Answer:

The second company job of $18 /hr is the better deal

Explanation:

We are told that;

-First job offers a salary of $30,000/yr

-Second job offers a salary of $18/hr.

Now, let's convert the salary of the second job to amount per year.

We are told that full-time work is 49hr/wk, 52 wk/yr.

Since we have 49 hrs in a week, then amount per week = 18 × 49 = $882 per week

Then amount per year = 882 × 52 = $45864 /yr

Thus, the second job pays $45864 /yr.

This is more than the first job. Thus, the second job is the better deal

Answer

In 1909, Robert Millikan and Harvey Fletcher conducted the oil drop experiment to determine the charge of an electron. ... Using the known electric field and the values of gravity and mass, Millikan and Fletcher determined the charge on oil droplets in mechanical equilibrium.

Millikan and fletcher determined the charge on oil droplets in mechanical equilibrium

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A solution is defined as a mixture of two or more substances, usually, a solute and a solvent, and the difference between these two are in quantity, solute represents the smallest amount and solvent will represent the highest amount, and while you can have more than one solute, you can only have one solvent for a solution. Therefore the statement is true

Liquid/liquid and acid/base reactions are commonly used in organic reactions to catalyze or facilitate the reaction. Organic reactions are chemical reactions involving organic compounds, which are molecules that contain carbon and hydrogen atoms.

Many organic reactions require a catalyst or a facilitator to occur, and liquid/liquid and acid/base reactions are often used for this purpose.

In liquid/liquid reactions, two liquid phases are used, and the reactants and catalysts are distributed between them. This can provide a favorable environment for the reaction to occur, such as by increasing the solubility of the reactants or by separating reaction intermediates from the main reaction.

In acid/base reactions, an acid or a base is used as a catalyst or a facilitator. Acids can donate a proton (H+) to the reactants, while bases can accept a proton. This can change the electronic properties of the reactants and make them more reactive, or it can stabilize the reaction intermediates.

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The statement that is true of entropy changes is the correct option is the entropy of a substance is influenced by the structure of the particles that comprise the substance.

The Heavier atoms will possess the greater entropy at the given temperature than the lighter atoms and the entropy of the substance will be  influenced by the structure of the particles that is comprise the substance. The Entropy is the measure of the randomness or the disorders .

The entropy decreases that is the ΔS < 0 as the substance will transforms from the gas to the liquid and then to the solid.

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Answer:

True

Explanation:

Because burning is a chemical reaction. Morever chemical change can not be reverse wood becomes ashes and smoke after burning and wood can not be again formed by ashes and smoke.

The equation for the hydrolysis of glyceryl triethanoate is C3H5(OH)3 + 3CH3COOH = C3H3(OCOCH3)3 + HOCH2CH(OH)CH2OH

Hydrolysis is a chemical reaction which water molecule break down one or more chemical bonds. This is use for substitution, elimination, and solubility.

Hydrolysis depend on the pH, solubility and chemical constituent of the substance.

Therefore, The equation for the hydrolysis of glyceryl triethanoate is C3H5(OH)3 + 3CH3COOH = C3H3(OCOCH3)3 + HOCH2CH(OH)CH2OH

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Answer: Earthquakes are usually caused when underground rock suddenly breaks and there is rapid motion along a fault. This sudden release of energy causes the seismic waves that make the ground shake.

Answer: This would cause an earthquake

Explanation:

The commonality between water vapour condensing on a bathroom mirror and beating an egg is that they both involve a change in state.

Water vapour condenses into liquid water on a mirror surface, while beating an egg transforms it from a liquid to a semi-solid state.

Water vapour condensing on a bathroom mirror: When hot water is used in a bathroom, the water vapour in the air comes into contact with the cooler surface of the mirror. This causes the water vapour to lose heat energy and change from a gas to a liquid, resulting in water droplets forming on the mirror.

Beating an egg: When you beat an egg, you are applying mechanical force to it by whisking or stirring. This force breaks the protein bonds in the egg, causing the liquid egg white and yolk to combine and form a homogeneous mixture. This change in state transforms the egg from a liquid to a semi-solid state.

In both cases, the substances undergo a physical change in their state. The water vapour condenses into liquid water, and the liquid egg transforms into a semi-solid mixture. This commonality is that the substances change from one state to another through the application of different conditions or forces.

This commonality lies in the fact that both changes involve transitions between different states of matter, brought about by specific conditions or forces.

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If you leave a sink dripping on the same spot on a bar of soap for 45 minutes, about 54 grams of soap will be eroded and the soap will weigh about 81 grams.

Answer:

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Answer:

You need 0.5 moles of oxygen to burn one mole of Mg.

Explanation:

The balanced reaction is:

2 Mg + O₂ → 2 MgO

When chemical changes occur, the chemical elements are conserved, so the number of atoms is the same before and after the change. To represent this equality of the number of atoms, the expression is "balanced" or "equalized". That's why you put a two in front of the magnesium formula and a two in front of the magnesium oxide to equal the number of atoms involved in the change. These numbers used are called stoichiometric coefficients. The stoichiometric coefficients allow to establish the molar ratio in which the reactants combine and the products are formed.

By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction) the following amounts of each compound participate in the reaction:

Then you can apply the following rule of three: if by reaction stoichiometry 2 moles of magnesium reacts with , 1 mole of magnesium reacts with how many moles of oxygen?

\(amount of moles of oxygen=\frac{ 1 mole of magnesium*1 mole of oxygen}{ 2 moles of magnesium}\)

amount of moles of oxygen= 0.5 moles

You need 0.5 moles of oxygen to burn one mole of Mg.

1. An increase in concentration increases the speed of reaction.

2. When temperature increases, average speed of molecules increases.

3. Average kinetic motion of molecules in a solution can be measured by measuring the heat in the solution.

As concentration increases, number of molecules in the solution increase, hence the reaction becomes faster. Since these factors increase in value, the frequency of collisions between the reactant molecules in the solution will increase, so the probability of collisions in right orientation and with right energy will be higher. Increase in temperature will increase the average speed and kinetic energy of the  molecules in solution. At constant volume, increased speed of reactant molecules in the solution will increase the probability of collisions in right orientation and right energy. Average kinetic energy of molecules in a solution can be measured using the equation, E=kT , where k = Boltzmann constant.

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Answer:

C. A much larger amount of silk might be needed to produce the same effect

Explanation:

As you may know it will take a lot of silk to make bullet proof fabric out of it.

Answer:

I Guess C

Explanation:

The availability of spider silk is not enough for what is needed, so i believe C is the right answer. But that means that B is also a bit correct .

The molecular formula of compound A is C₂H₅., the molecular formula for compound B is C₇H₁₄.

Empirical formula is the most straightforward formula for a compound and provides the ratio of various atoms found in each compound molecule.

The empirical formula for the two compounds is CH₂. To determine the molecular formula, we need to know the molar mass of the compounds.

If the molar mass of compound A is 60.05 g/mol, and the empirical formula is CH₂, we can calculate the molecular formula by dividing the molar mass by the molar mass of the empirical formula.

60.05 g/mol / (12.01 g/mol + 2 x 1.01 g/mol) = 2.5

Therefore, the molecular formula for compound A is C₂H₅

Similarly, if the molar mass of compound B is 180.16 g/mol, and the empirical formula is CH₂, we can calculate the molecular formula by dividing the molar mass by the molar mass of the empirical formula.

180.16 g/mol / (12.01 g/mol + 2 x 1.01 g/mol) = 7.5

Therefore, the molecular formula for compound B is C₇H₁₄.

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Approximately 777.6 grams of water is needed to make 7.2 moles of glucose based on the balanced equation.

The balanced equation provided is:

6CO2 + 6H2O -> C6H12O6 + 6O2

From the equation, we can see that for every 6 moles of water (H2O), 1 mole of glucose (C6H12O6) is produced. Therefore, we need to determine the amount of water required to produce 7.2 moles of glucose.

The mole ratio between water and glucose is 6:1. This means that for every 6 moles of water, we obtain 1 mole of glucose. To find the amount of water needed for 7.2 moles of glucose, we set up a proportion using the mole ratio:

(6 moles H2O / 1 mole glucose) = (x moles H2O / 7.2 moles glucose)

Solving for x, we can cross-multiply:

6 moles H2O * 7.2 moles glucose = x moles H2O * 1 mole glucose

43.2 moles H2O = x moles H2O

Therefore, we need 43.2 moles of water to produce 7.2 moles of glucose.

To convert moles of water to grams, we need to know the molar mass of water, which is approximately 18 g/mol. Using the molar mass, we can calculate the mass of water needed:

Mass of water = moles of water * molar mass of water

Mass of water = 43.2 moles * 18 g/mol

Mass of water = 777.6 g

Therefore, approximately 777.6 grams of water is needed to make 7.2 moles of glucose based on the balanced equation.

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The mass of iron produced when 11.0 g of aluminum reacts with 30.0 g of iron (III) oxide is approximately 10.48 grams.

To determine the mass of iron produced when 11.0 g of aluminum reacts with 30.0 g of iron (III) oxide, we need to balance the chemical equation and perform stoichiometric calculations.

The balanced chemical equation for the reaction between aluminum and iron (III) oxide can be written as follows:

2 Al + Fe₂O₃ → 2 Fe + Al₂O₃

From the balanced equation, we can see that 2 moles of aluminum react with 1 mole of iron (III) oxide to produce 2 moles of iron and 1 mole of aluminum oxide.

Convert the given masses of aluminum and iron (III) oxide into moles.

Using the molar mass of aluminum (26.98 g/mol) and iron (III) oxide (159.69 g/mol), we can calculate the number of moles for each substance.

Number of moles of aluminum = mass of aluminum / molar mass of aluminum

= 11.0 g / 26.98 g/mol

= 0.408 moles

Number of moles of iron (III) oxide = mass of iron (III) oxide / molar mass of iron (III) oxide

= 30.0 g / 159.69 g/mol

= 0.188 moles

Determine the limiting reactant.

To determine the limiting reactant, we compare the stoichiometric ratio of aluminum to iron (III) oxide. From the balanced equation, we see that 2 moles of aluminum react with 1 mole of iron (III) oxide.

Given that we have 0.408 moles of aluminum and 0.188 moles of iron (III) oxide, we can calculate the moles of iron that can be produced from each reactant.

Moles of iron from aluminum = 2 * 0.408 moles = 0.816 moles

Moles of iron from iron (III) oxide = 0.188 moles

Since the moles of iron from aluminum (0.816 moles) is greater than the moles of iron from iron (III) oxide (0.188 moles), we can conclude that iron (III) oxide is the limiting reactant.

Calculate the mass of iron produced.

To calculate the mass of iron produced, we use the molar mass of iron (55.85 g/mol) and the number of moles of iron from the limiting reactant.

Mass of iron = moles of iron from iron (III) oxide * molar mass of iron

= 0.188 moles * 55.85 g/mol

= 10.48 g

Therefore, the mass of iron produced when 11.0 g of aluminum reacts with 30.0 g of iron (III) oxide is approximately 10.48 grams.

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The reaction between pottasium metal and chlorine gas is a combination reaction and it is as follows;

2K + Cl₂ → 2KCl

A chemical reaction is a process involving the breaking or making of interatomic bonds, in which one or more substances are changed into others.

A chemical reaction is said to be a combination reaction when two or more atoms are joined together to form a compound. An example is the reaction of pottasium metal and chlorine gas to produce pottasium chloride as follows:

2K + Cl₂ → 2KCl

In the above equation, two elements; pottasium chemically combines with chlorine to form a compound; pottasium chloride.

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Answer:

KNO3 (Potassium Nitrate)

Explanation:

I just know.

Answer:

Almost everything in our surroundings represent chemical change

Explanation:

●Rusting of iron in presence of moisture and oxygen.

●Burning of wood.

●Milk becoming curd.

●Formation of caramel from sugar by heating.

●Baking of cookies and cakes.

●Cooking any food.

●Acid-base reaction.

●Digestion of food.

The heat of reaction (ΔH) for the given reaction is 180.4 kJ/mol. To calculate the heat of reaction (ΔH) for the given reaction:

CCl₄(g) + H₂O(g) -> CHCl₃(g) + HCl(g)

You would need the standard enthalpies of formation for each compound involved in the reaction. The standard enthalpy of formation (ΔHf) is the enthalpy change when one mole of a compound is formed from its elements in their standard states.

Here are the standard enthalpies of formation for the compounds involved:

ΔHf[CCl₄(g)] = -135.5 kJ/mol

ΔHf[H₂O(g)] = -241.8 kJ/mol

ΔHf[CHCl₃(g)] = -104.7 kJ/mol

ΔHf[HCl(g)] = -92.3 kJ/mol

To calculate ΔH for the reaction, you need to sum up the enthalpies of formation of the products and subtract the sum of the enthalpies of formation of the reactants:

ΔH = ΣΔHf(products) - ΣΔHf(reactants)

ΔH = [ΔHf[CHCl₃(g)] + ΔHf[HCl(g)]] - [ΔHf[CCl₄(g)] + ΔHf[H₂O(g)]]

ΔH = [(-104.7 kJ/mol) + (-92.3 kJ/mol)] - [(-135.5 kJ/mol) + (-241.8 kJ/mol)]

ΔH = -196.9 kJ/mol - (-377.3 kJ/mol)

ΔH = 180.4 kJ/mol

Therefore, the heat of reaction (ΔH) for the given reaction is 180.4 kJ/mol.

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Answer:

The correct answer is B. Cs+ represents a cesium ion.

Based on the calculations performed in this experiment, the same mass of a solute with a significantly higher molar mass would have a larger effect on the boiling point elevation. As a result, the same mass of a solute with a higher molar mass will have a greater effect on the boiling point elevation.

Boiling point elevation is a thermodynamic phenomenon that occurs when the boiling point of a solvent (a substance that dissolves a solute to create a solution) is increased by adding another substance, the solute, to it. When a solute is added to a solvent, it lowers the freezing point and raises the boiling point of the solvent, which is known as the boiling point elevation.The formula for boiling point elevation is: ∆Tb = Kbm

Here, ∆Tb is the boiling point elevation, Kb is the molal boiling point elevation constant, and m is the molality of the solution. To understand this, let us take an example: Suppose a solution containing 1.0 mol of sodium chloride (NaCl) is dissolved in 1.0 kg of water. The molality of the solution is 1.0 mol / 1.0 kg = 1.0 m. In addition, the Kb for water is 0.51 °C/molal, which means that the boiling point elevation is 0.51 °C when the molality of the solution is 1.0 mol/kg.So, the boiling point of the solution will be raised by 0.51 °C, which can be calculated using the above formula.Calculation performed in this experiment:Boiling point elevation = ΔTb = Kb . mTherefore, based on the above formula, the boiling point elevation is directly proportional to the molality of the solution, which, in turn, is directly proportional to the number of moles of solute in the solution. Furthermore, the number of moles of solute is proportional to the mass of the solute (in grams) divided by its molar mass (in grams/mol).So, if a solute with a significantly higher molar mass is added to the solvent, it will have a larger effect on the boiling point elevation. As a result, the same mass of a solute with a higher molar mass will have a greater effect on the boiling point elevation.

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Answer: Copper is purified by electrolysis . Electricity is passed through solutions containing copper compounds, such as copper(II) sulfate. The anode (positive electrode ) is made from impure copper and the cathode (negative electrode) is made from pure copper. Pure copper forms on the cathode.