Determine whether each observation generally corresponds to a physical change or a chemical change. A liquid freezes into a solid. _________ Bubbles are produced upon mixing two solutions. __________ A precipitate is formed from two solutions. _________ A solution heats up upon mixing with another. ____________ A solid dissolves into water. __________ The color of a substance changes over time

The solubility of the salts is affected by the temperature changes. 1. NaCl is least affected by temperature. 2. supersaturated. 3. 60 grams KBr. 4. Ethanol has both polar and non-polar groups. 5. Mixing and shaking.

A KBr solution with 90 gm solute in 100 grams of water at 50 degrees is classified as supersaturated. 60 grams of KBr are needed to make a saturated solution in 100 gm of water at 30 degrees.

Ethanol is a general solvent due to the presence of both the polar and the non-Polar groups. As a result, it is easier to dissolve both polar molecules and non-Polar molecules. The dissolving rate can be increased by mixing or shaking the solution. Also, the sugar dissolves faster in hot than cold tea.

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The grams solutes ini 835 mL of 0.390 M KBr is 38.75 g.

The grams can be calculated as follows:

The first you should calculate the molar

Times the molar of KBr by its valume to get moles

n = Molar x volume

n = 0.390 M x 0.835L

n = 0.32565 moles

thus, you should calculate molar mass so you can calculate the gram

Mass of potasium = 39.10 g/mol

Mass of Bromine = 79.904 g/mol

mass molar = 39.1 g/mol+79.9 g/mol = 119 g/mol

The next step is calculate the gram by time the moles to  its mass molar

gram = n x mass molar

gram = 0.32565 moles x 119 g/mol= 38.75 g.

so, The grams solutes ini 835 mL of 0.390 M KBr is 38.75 g.

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From the diagram that is shown;

a. The letter B

b. The letter C

c. It is an exothermic reaction

d. Letter A

e. Letter D

f. Letter D

g. Letter A

The progression of a chemical reaction from the reactants (beginning materials) to the products (end products) is conceptually represented by the reaction coordinate. It offers a means of observing and evaluating the energy shifts and structural modifications that take place throughout a reaction.

The horizontal axis of a reaction coordinate diagram or energy profile shows how the reaction is progressing, usually from left to right. The system's potential or free energy is shown on the vertical axis. The reaction coordinate can be expressed in terms of separation, bond length, or any other appropriate parameter that accurately characterizes the reaction's progress.

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Both changing particle size and adding a catalyst can influence the reaction rate, while adding heat specifically affects the rate by increasing the kinetic energy of the reactant particles.

The correct option are A and C.

Both changing particle size and adding a catalyst can alter the reaction rate.

Changing particle size can affect the reaction rate because it influences the surface area available for the reactant particles to interact. Smaller particle sizes result in a larger surface area, increasing the frequency of collisions between particles and accelerating the reaction. Conversely, larger particle sizes reduce the surface area, leading to fewer collision events and slower reaction rates.

Adding heat can also alter the reaction rate. Increasing the temperature provides more thermal energy to the reactant particles, causing them to move faster and collide with greater energy. This enhanced kinetic energy leads to more successful collisions and an increased reaction rate.

Adding a catalyst can significantly affect the reaction rate. A catalyst provides an alternative reaction pathway with lower activation energy, enabling the reaction to occur more easily. By lowering the energy barrier, a catalyst increases the rate of reaction without being consumed or permanently altered in the process.

The correct option are A and C.

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Answer:

A

Explanation:

Two specialized cells called 'guard cells' make up each stoma (stoma is singular for stomata). Plants have many stomata up to 400 per mm2 on their leaf surfaces and they are usually on the lower surface to minimize water loss.

Answer and Explanation:

Yes. The determination of melting point is used to analyze if a solid compound is pure or impure. The melting point of a pure solid product does not vary in a narrow range, whereas if impurities are present the solid melts in a broad range of temperatures. For this reason, this technique is generally used to determine the identity and purity of the products obtained in chemical reactions.

The enthalpy of combustion for 1kg of urea is -1223525.84 J/mol.

Urea is a compound that is used in fertilizers and in some plastics.The enthalpy of combustion for urea is the amount of energy that is released when urea is burned. In order to calculate the enthalpy of combustion for 1kg of urea, we need to use the information that is provided to us in the question. Let us start by writing down the balanced equation for the combustion of urea: CO(NH2)2 + 3/2 O2 → CO2 + 2H2O + N2
The balanced equation shows that 1 mole of urea reacts with 1.5 moles of oxygen gas to produce 1 mole of carbon dioxide, 2 moles of water, and 1 mole of nitrogen gas. The enthalpy change for this reaction is equal to the amount of energy that is released when 1 mole of urea is burned.
The heat of combustion (ΔHc) of urea is -632.6 kJ/mol. This means that 632.6 kJ of energy is released when 1 mole of urea is burned. We know that 12g of urea raised the temperature of water by 30°C. We can use this information to calculate the amount of energy that was released when 12g of urea was burned.
The specific heat capacity of water is 4.18 J/g°C. This means that it takes 4.18 J of energy to raise the temperature of 1 gram of water by 1°C. Therefore, it takes 4.18 x 1000 = 4180 J of energy to raise the temperature of 1 kg of water by 1°C.
We know that 12g of urea raised the temperature of water by 30°C. Therefore, the amount of energy that was released when 12g of urea was burned is:
Energy = mass x specific heat capacity x temperature change
Energy = 0.012 kg x 4180 J/kg°C x 30°C
Energy = 1497.6 J
We can now use this information to calculate the enthalpy of combustion for 1kg of urea:
Enthalpy of combustion = energy released / moles of urea burned
Enthalpy of combustion = 1497.6 J / (0.012 kg / 60.06 g/mol)
Enthalpy of combustion = - 1223525.84 J/mol
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Answer:

Plates at our planet's surface move because of the intense heat in the Earth's core

Explanation:

Hopefully this helps, I believe in you! ^^

Answer/Explanation:

movement can be cause by the intense heat in the earth's core, which causes molten rock in the mantle layer to move.  it moves in a pattern called 'convection cell' which can form when the warm material rises, then cools, and eventually sink down.  then the process repeats (cooled, warms up and rises.. etc..)

I hope this was what you were kinda looking for:) - T

PS. HAVE A GOOD DAY! I LIKEYOUR PROFILE HAFHAS

Answer:

The empirical formula is C4H8O

Explanation:

Step 1: Data given

Valproic acid is composed of C, H, and O

Mass of the sample = 0.165 grams

Mass of water = 0.166 grams

Mass of CO2 = 0.403 grams

Molar mass of water ( H2O) = 18.02 g/mol

Molar mass of CO2 = 44.01 g/mol

Atomic mass of C = 12.01 g/mol

Atomic mass of O = 16.0 g/mol

Atomic mass H = 1.01 g/mol (H2 = 2.02 g/mol)

Step 2: The equation

CxHyOz + O2 → CO2 + H2O

Step 3: Calculate the number of carbon in the sample

The carbon comes from CO2

Mass C = (12.01 g/mol/44.01 g/mol) * 0.403 grams

Mass C = 0.110 grams

Step 4: Calculate mass of hydrogen in the sample

The hydrogen comes from H2O

Mass H = (2.02/18.02) * 0.166 grams

MAss H = 0.0186 grams

Step 5: Calculate mass of O

The mass of O in the sample = Mass of sample - mass of H - mass of C

The mass of O = 0.165 grams - 0.110 grams - 0.0186 grams

The mass of O = 0.0364 grams

Step 6: Calculate moles

Moles C = 0.110 grams / 12.01 g/mol = 0.00916 moles

Moles H = 0.0186 / 1.01 = 0.0184 moles

Moles O = 0.0364/16.0 = 0.00228 moles

Step 7: Calculate empirical formula

We divide by the smallest amount of moles

C: 0.00916/ 0.00228 = 4

H: 0.0184/0.00228 = 8

O: 0.00228/0.00228 = 1

The empirical formula is C4H8O

The molar mass of a gas with a density of 1.02 g/L at 2.13 atm and a temperature of 20°C is 47.9 g/mol.The molar mass of an element or compound is the mass of one mole of that substance. A mole is the SI unit for the amount of a substance.

It's defined as the amount of a substance that contains the same number of entities as there are atoms in 12 grams of carbon-12.Molar mass (M) = mass (m) ÷ amount of substance (n)So, M = m/n

Where m is the mass in grams and n is the number of moles. The unit of molar mass is grams per mole (g/mol).

The ideal gas law is used to calculate the molar mass of a gas. The ideal gas law is:P V = n R T,Where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature.

Convert the density to grams per liter: 1.02 g/L.

The density is mass/volume, thus 1.02 g/L means that 1 liter of the gas weighs 1.02 g.

This means that 1 mole of gas will occupy 22.4 L (at standard temperature and pressure, STP).Calculate the number of moles of gas using PV = nRT.P = 2.13 atmV = 22.4 L (at STP)R = 0.0821 L·atm/K·molT = 273.15 K + 20 K = 293.15 K

Thus, n = PV/RT = (2.13 atm × 22.4 L)/(0.0821 L·atm/K·mol × 293.15 K) = 0.973 mol

Calculate the molar mass (M) using M = m/n.m = density × volume = 1.02 g/L × 22.4 L = 22.848 gM = m/n = 22.848 g/0.973 mol = 23.5 g/mol Convert to units of grams per mole: 23.5 g/mol

The molar mass of a gas with a density of 1.02 g/L at 2.13 atm and a temperature of 20°C is 47.9 g/mol.

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Answer: Industrial processes including mining and manufacturing historically have been leading causes of soil pollution. Industrial areas typically have much higher levels of trace elements and organic contaminants. This is due to intentional and unintentional releases from industrial processes directly into the environment, including to the soil, adjacent water bodies, and the atmosphere.

Explanation:

When fossil fuels burn, several forms of energy are produced, including:

Heat energy: The primary form of energy released during fossil fuel combustion is heat. Fossil fuels contain chemical energy stored for millions of years, and when they burn, this energy is released in the form of heat. The heat energy can be harnessed for various purposes, such as heating buildings or generating steam to drive turbines.

Light energy: Burning fossil fuels can also produce light energy in the form of flames or glowing embers. This light energy is a byproduct of combustion.

Mechanical energy: Heat generated by burning fossil fuels can be converted into mechanical energy. This is typically achieved by using heat to produce steam, which drives a turbine connected to a generator. The rotating turbine converts the heat energy into mechanical energy, which is further transformed into electrical energy.

Electrical energy: Through the process described above, burning fossil fuels can ultimately generate electrical energy. The mechanical energy produced by the turbine is converted into electrical energy by the generator. Electrical energy can power various devices, appliances, industries, and infrastructure.

It's critical to note that while burning fossil fuels can produce useful forms of energy, it also results in the release of carbon dioxide and other greenhouse gases. This contributes to climate change and environmental concerns. As a result, there is a global shift towards cleaner and renewable energy sources to mitigate these negative impacts.

11. The concentration of C is 200

12. The concentration of B is 0.4

Equilibrium constant, K is defined as follow:

nReactant ⇌ mProduct

Equilibrium constant, K = [Product]ᵐ / [Reactant]ⁿ

With the above formula, we can obtain the equilibrium concentration of the missing substance as follow:

11. For concentration of C

K = [C] / [A][B]

20 = [C] / (2 × 5)

20 = [C] / 10

Cross multiply

[C] = 20 × 10

Concentration of C, [C] = 200

12. For concentration of B

K = [C] / [B]

10 = 4/ [B]

Cross multiply

10 × [B] = 4

Divide both sides by 10

[B] = 4 / 10

Concentration of B, [B] = 0.4

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Complete question:

Find the concentration of the missing substance

11) A + B = C

K = 20

[A] = 2

[B] = 5

[C] =?

12) A(s) + B(ag) = C(g)

K = 10

[C] = 4

[B] = ?

Answer:

\(\Large \boxed{\sf 0.714 \ moles}\)

Explanation:

Avogadro's number can be used as a conversion factor from atoms to moles or moles to atoms.

\(\displaystyle \frac{4.3 \times 10^{23}}{6.022 \times 10^{23} } =0.714048\)

The answer is D) 5 × 10⁻³.

The equilibrium constant expression for the reaction is given by:

\(K = [H_3O^+]^2 [C_2O_4^{-2}] / [H_2C_2O_4]\)

Since oxalic acid is a diprotic acid, its dissociation occurs in two steps, and the given values of Kx and K2 correspond to the dissociation constants of the first and second steps, respectively. The overall dissociation constant, K, can be expressed in terms of Kx and K2 as:

K = Kx × K2

Substituting the given values of Kx and K2:

K = 5 × 10⁻⁵ × 5 × 10⁻¹⁰

K = 2.5 × 10⁻¹⁴

Comparing the calculated value with the options given:

A) 5 × 10² - Not equal

B) 5 × 10¹⁰ - Not equal

C) 25 × 10⁻¹ - Not equal

D) 5 × 10⁻³ - Equal

Therefore, the answer is D) 5 × 10⁻³

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Answer:

carbon and silicon

Explanation:

Various groups of elements in the periodic table have different outermost shell electron configurations. Actually, elements are classified into groups on the basis of the number of electrons on the outermost shell of those elements. All elements with the same number of electrons on their outermost shell belong to the same group in the periodic table.

For elements in group 14, they all have four electrons on their outermost shell. Their general outer electron configuration is ns2 np2 as shown in the question. Two prominent members of this group are carbon and silicon. This ns2 np2 is the ground state outer electron configuration of all group 14 elements in the periodic table.

yes they can be changed becasue they are expose to the environment

That's why it's improtant to have a calorimeter so the energy and heat are contained

The total energy of an open system be changed if:

According to the First Law of Thermodynamics, energy cannot be created or destroyed, it can only change form.

An open system is a system that has an interaction with its environment where matter or energy can be added or removed from the environment.

As a result of this, the total energy of an open system can be changed if there is an exchange between matter and energy and they remain constant.

Therefore, the correct answer is an exchange has to take place for the total energy in an open system to be changed.

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The learning activities titled "Hypothesis," "Variables and Hypothesis," and "Constructing a Hypothesis" all share certain similarities and differences. A question that arises in response to an observation is similar to a scientific research question in that both require some level of investigation to achieve an answer. However, scientific research questions are typically more specific and refined, with a defined methodology for obtaining data and verifying results.

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The volume of a 0.220 M HBr solution required to produce 0.0120 moles of HBr is 54.5 mL.

To calculate the volume of a 0.220 M HBr solution required to produce 0.0120 moles of HBr, we can use the following formula:

Volume (in liters) = moles / concentration

First, we need to convert the moles of HBr to liters:

0.0120 moles / (0.220 mol/L) = 0.0545 L

Next, we can convert liters to milliliters:

0.0545 L x 1000 mL/L = 54.5 mL

Therefore, the volume of a 0.220 M HBr solution required to produce 0.0120 moles of HBr is 54.5 mL.

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Answer:

Solid piece of ice.

Explanation:

Solid piece of ice can easily melt due to heat radiation

Answer:

Carbon dioxide concentrations are rising mostly because of the fossil fuels that people are burning for energy.Aug 14, 2020

Explanation:

Answer:

2H2O+O2-2H2O2

Explanation:

TO BALANCE equation both side should be equal

Answer:

heterogeneous mixture.

Explanation:

Fog is heterogeneous mixture of water, air and suspension particles.

The C2 electron configuration is (2s)2, (*(2s)2), (2p)x2, ((2p)y2), ((2p)x1, and ((2p)y2). C2+ has 11 valence electrons because it has one fewer electron than C2. the following chemical orbital diagram: 1 g2 1 u2 2 g2 2 u2 1 g2 3 g2 1 g2.

One electron is taken away from C2 to create C+2. The molecular orbital diagram can be used to determine the bond arrangement of C+2. Therefore, C+2 has a bond rank of 1.5.

Cu 2 + ion has the electronic structure [Ar] 3 d 9. The d-orbital contains one lone electron. It is therefore paramagnetic.

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The amount of heat energy produced when 1 g of hydrogen and 2 g of nitrogen are reacted, is -6.61 KJ

First, we shall obtain the limiting reactant. Details below:

3H₂ + N₂ -> 2NH₃

From the balanced equation above,

28 g of N₂ reacted with 6 g of H₂

Therefore,

2 g of N₂ will react with = (2 × 6) / 28 = 0.43 g of H₂

We can see that only 0.43 g of H₂ is needed in the reaction.

Thus, the limiting reactant is N₂

Finally, we the amount of heat energy produced. Details below:

3H₂ + N₂ -> 2NH₃ ΔH = -92.6 KJ

From the balanced equation above,

When 28 grams of N₂ reacted, -92.6 KJ of heat energy were produced.

Therefore,

When 2 grams of N₂ will react to produce = (2 × -92.6) / 28 = -6.61 KJ

Thus the heat energy produced from the reaction is -6.61 KJ

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The value of  Kc for each reaction. b. CH4(g) + H2O(g) ⇌ CO(g) + 3 H2(g) is Kp =\(7.7x10^24  mol^-1\)

To calculate Kc for a reaction, we need to use the relationship between Kp and Kc, which is: Kc =\(Kp (RT)^(Δn)\)

where R is the ideal gas constant, T is the temperature in Kelvin, and Δn is the change in the number of moles of gas in the reaction.

For the reaction: CH4(g) + H2O(g) ⇌ CO(g) + 3 H2(g)

Δn = (3 - 2) - (1 - 1) = 1

So, Kc =\(Kp (RT)^(Δn)\)

At 298 K, R = 8.314 J/\(mol*K\), so

Kc =\(7.7x10^24 (8.314 J/mol*K)(298 K)^1\)

Kc = \(7.7x10^24 J/mol\)

Since Kc is in Joules, we can convert it to an appropriate unit of concentration.

Kc=\(7.7x10^24 mol^-1\)

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Kc ≈ 1.8 x 10⁻⁷ (at 298 K). It indicates a strong preference for the forward reaction, forming products, under the given conditions.

To calculate Kc for the given reaction, we need to use the relationship between Kc and Kp and the ideal gas law.

The relationship between Kc and Kp for a balanced chemical equation is:

\(Kp = Kc * (RT)^Δn\)

Where:

Kp is the equilibrium constant in terms of partial pressures.

Kc is the equilibrium constant in terms of molar concentrations.

R is the ideal gas constant (8.314 J/(mol·K)).

T is the temperature in Kelvin.

Δn is the difference in the number of moles of gaseous products and gaseous reactants.

In the given reaction, Δn = (1 + 3) - (1 + 1) = 2.

Now, we can rearrange the equation to solve for Kc:

\(Kc = Kp / (RT)^Δn\)

Given Kp = 7.7 x 10²⁴ and T = 298 K, and substituting the values, we get:

Kc ≈ (7.7 x 10²⁴) / [(8.314 J/(mol·K) * 298 K)²]

Kc ≈ 1.8 x 10⁻⁷

Thus, Kc for the reaction is approximately 1.8 x 10⁻⁷ at 298 K.

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The Kinetic Molecular Theory is a  scientific model that states atoms in a compound are found in a constant state of motion (movement).

The Kinetic Molecular Theory is a  scientific model that states atoms in a compound are found in a constant state of motion (movement).

Thermal energy refers to the movement of particles and therefore both concepts are interrelated.

In conclusion, the Kinetic Molecular Theory is a  scientific model that states atoms in a compound are found in a constant state of motion (movement).

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