energy being released like when fireworks are set off are an example of physical or chemical change

Answer

Mendeleev predicted the properties of undicovered elements such as Germanium. He ddeuced based on the gaps in the periodic tbl

Yes, it will be harder to get the strong magnets to change phase​ because the molecules are tightly packed together.

This is referred to as a material which has the ability to produce its own magnetic field and consists of north and south poles. It is usually made from substances such as iron and is usually hard.

In a magnet, the like poles repel and the unlike poles attract and in this scenario, it will be harder to get the strong magnet to 'change phase' as a result of the atomic structure of the substances involved.

They are in the form of solids, which means that there is very little or no space between the atoms. This translates to a higher force of attraction and strong bonding thereby making it the most appropriate choice.

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• We need to take into consideration that many factors lead to variations from the ideal bond angles of a molecular shape. Size of the atoms involved, presence of lone pairs, multiple bonds, large groups attached to the central atom,

• In this instance,, Option 2,3,4, are applicable in order to cause bond angles to differ between molecules.

Mix the mixture with water, filter off the insoluble solids and evaporate the water to separate the soluble solids.

This gives a heterogeneous mixture, one with dissolved solids and one with undissolved solids, you can see two different phases

These two A simple filtration method can be used to separate the two phases.

Filtering the mixture yields a solution containing soluble solids, leaving the insoluble solids on the filter paper.

This will separate the two solids.

Water can be heated and evaporated to regenerate dissolved solids. This will return the original soluble solids.

So the only option consistent with this method is to "mix the mixture with water, filter off the insoluble solids, then evaporate the water to separate the soluble solids".

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In electrolysis, the anode is positively charged while cathode is negatively charged

So, Cu2+ moves towards the negative electrode which is cathode

while SO42- moves towards anode

Since cathode(being negatively charged) rich in electrons, Cu2+ gains 2 electrons and sticks to the electrode and becomes Cu (solid form)

While, on anode, SO42- should go to loose electrons but this doesnt happen as it requires lot of energy to do that (overvoltage)

Instead, anode (which is itself made of Cu) starts loosing electrons and starts dissolving to release Cu2+ ions (as this process will require less energy)

So, in the electrolysis of CuSo4 using Cu electrodes,

Cathode reaction: Cu2+ + 2 e ---> Cu

Anode reaction: Cu ---> Cu2+ + 2e

For this question we will find the empirical formula and the molecular formula for a compound made of 39.7458% of C, 2.77956% of H, 13.4050% of Mg, and 44.0697% of Br. The mass we are calculating will be 181.33g/mol. The first thing we need to do is to find out how many grams of each element we actually have:

181.33g/mol = 100%

x grams = 39.7458%

x = 72.07 grams of C

181.33 = 100%

x grams = 2.77956%

x = 5.04 grams of H

181.33 = 100%

x grams = 13.4050%

x = 24.307 grams of Mg

181.33 = 100%

x grams = 44.0697%

x = 79.91 grams of Br

Now we have the mass for each element, we need to find the number of moles that each element has based on their masses and the molar mass of each one:

Carbon = 12g/mol

H = 1g/mol

Mg = 24.305g/mol

Br = 79.9g/mol

For Carbon:

12g = 1 mol

72.07g = x moles

x = 6 moles of C

For Hydrogen:

1g = 1 mol

5.04g = x moles

x = 5 moles of H

For Magnesium:

24.305g = 1 mol

24.307g = x moles

x = 1 mol of Mg

For Bromide:

79.90g = 1 mol

79.91g = x moles

x = 1 mol of Br

The molecular formula for this compound will be C6H5MgBr, this is Phenylmagnesium bromide, this will also be its empirical formula, since there is no way we can divide the numbers and make an empirical formula.

To predict how many electrons an element can gain or lose, we can be guided by the group to which it belongs in the periodic table. Chlorine belongs to group VII of the periodic table. This means that it has 7 valence electrons.

According to the octet rule, for an atom to be stable it must have 8 electrons in its last energy level, this means that chlorine can gain one electron to comply with the octet rule.

So, the answer will be: a.1

Answer

Explanation

Given:

Mass of iron (III) oxide sample = 74 g

What to find:

The amount (mole) of iron (III) oxide in a 74 g sample.

Solution:

The amount (mole) of iron (III) oxide in a 74 g sample can be calculated using the mole formula.

Using the molar masses of Fe = 55.845 g/mol, and O = 15.999 g/mol.

The molar mass of Fe2O3 = (2 x 55.845) + (3 x 15.999) = 159.687 g/mol

Putting mass = 74 g and molar mass = 159.687 g/mol, the amount will be

Therefore, the amount of iron (III) oxide in a 74 g sample is approximately 0.46 moles.

The equation of the enthalpy of the formation of water is:

H₂O (g) + ¹/₂ O₂ (g)----> H₂O (g)

The enthalpy change for the formation of water refers to the heat changes that occur when a mole of water is formed from its constituent elements.

The equation for the formation of water is given below:

2 H₂O (g) + O₂ (g)----> 2 H₂O (g)

The enthalpy of the formation of water, ΔHf, is -249 kJ.

A water molecule s formed from the hydrogen gas and oxygen gas reacting with a mole ratio of 2 : 1.

The reaction of the formation of water is an exothermic reaction, hence, the enthalpy of the formation of water, ΔHf, has a negative value.

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The calculated concentration of the acetic acid neutralized is 0.134 M.

In this case, the task that we have is to obtain by calculation what would be the concentration of the acetic acid that is need to neutralize  0.1098M of sodium hydroxide solution.

Given that;

Total volume of the vinegar = 5 ml + 25 mL = 30 mL

Molarity of the sodium hydroxide =  0.1098M

Volume used for neutralization = 37.83ml -  1.35 ml = 36.48 mL

Applying the relation;

CAVA/CVB = NA/VB

CAVANB = CBVBNA

CA= CBVBNA/VANB

CA = 0.1098 * 36.48  * 1/30 * 1

CA = 0.134 M

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Answer

The model which best represents a molecule of hydrogen peroxide (H2O2) is option B.

Answer

a) Group 16

b) Group 1

c) Group 15

d)

e)

f) Sodium

g) Oxygen

h) Phosphorus

Procedure

Using the periodic table below identify the elements. The periodic table organizes elements in a way that reflects their number and pattern of electrons. The table places elements into columns—groups—and rows—periods.

An element’s column number gives information about its number of valence electrons and reactivity. In general, the number of valence electrons is the same within a column and increases from left to right within a row. Applies only for groups 1,2, 13-18 (remembering that from 13 to 18 the last number is the valence).

Answer: A: Chewing and chemical

Explanation:

Chewing is mechanical being that chemicals are not breaking down anything your teeth are.  

The question requires us to calculate the mass of 6.30 moles of Ca(OH)2.

To calculate the mass of the given number of moles of Ca(OH)2, first we need to calculate the molar mass of this compound and then multiply it by the number of moles given.

- Calculating the molar mass:

We calculate the molar mass from the atomic mass of the elements Ca, O and H (the elements present in the molecule) and considering the number of atoms of this elements.

The atomic masses are:

atomic mass (Ca) = 40.08 u

atomic mass (O) = 15.99 u

atomic mass (H) = 1.01 u

There is 1 atom of Ca, 2 atoms of O and 2 atoms of H in the molecule. Thus, we calculate the molar mass of Ca(OH)2 as:

molar mass Ca(OH)2 = (1 * 40.08) + (2 *15.99) + (2 * 1.01) = 74.08 g/mol

- Calculating the mass of 6.30 moles of Ca(OH)2:

Now that we have the molar mass of Ca(OH)2, we can use it to calculate the mass of the given number of moles of this compound. To do that, we'll use the following equation:

where n is the number of moles, m is the mass and M is the molar mass.

The calculation we need to do, with units, is as it follows:

Therefore, the mass of 6.30 moles of Ca(OH)2 is 466.7 g.

The geometrical chemistry name of the given structure is tetrahedral geometry or Sp3 hybrid structure and the hybridisation is called Sp3 hybridisation .

The process of combining the characteristics of one 2s orbital and three 2p orbitals to produce four hybrid orbitals with similar properties is known as "sp3 hybridization." An atom needs three p orbitals and a s orbital in order to be sp3 hybridized.

Tetrahedral hybridization, or sp3, is the process by which one's' orbital and three 'p' orbitals from the same atomic shell combine to generate four new equivalent orbitals. Sp3 hybrid orbitals are the new orbitals that have generated.

These form an angle of 109°28' with one another and are pointed at the four corners of a conventional tetrahedron.

The sp3 hybrid orbitals are at an angle of 109.280 degrees.

25% s character and 75% p character make up each sp3 hybrid orbital.

Ethane (C2H6) and methane are two examples of sp3 hybridization.

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      We produce trash. Every time we produce something, waste is typically produced. That trash was referred to by Dr. Seuss as "Gluppity Glup" and "Schloppity-Schlopp." Whatever we choose to call it, waste can become a problem if it isn't handled appropriately.

We produce trash. Every time we produce something, waste is typically produced. That trash was referred to by Dr. Seuss as "Gluppity Glup" and "Schloppity-Schlopp." Whatever we choose to call it, waste can become a problem if it isn't handled appropriately.

   Using the literary device of personification to create relatable characters for industry (as the Once-ler), the environment (as the Truffula trees), and environmental activism, the tale is widely regarded as a fable on the danger of avarice causing human damage of the natural environment.

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ANSWER

STEP-BY-BY STEP EXPLANATION:

Given equation

To balance the above equation, we will need to apply the law of conservation of mass

The next process is to assign variables to each of the reactants and products

For carbon

we have 1 carbon atom at the reactant side and 1 carbon atom on the product side

Mathematically

a = c

For Fluorine

We have 4 atoms of fluorine at the reactant side and 2 atoms of fluorine at the product side

4a = 2d

For Bromine

we have 2 atoms of bromine on the reactant side and 4 bromine atoms on the product side.

2b = 4c

Since a = c

Therefore, a = 1 and c = 1

2b = 4c

Recall that, c = 1

2b = 4

Divide both sides by 2

2b/2 = 4/2

b = 2

we also know that, 4a = 2d

a = 1

4(1) = 2d

4 = 2d

Divide both sides by 2

4/2 = 2d/2

d = 2

Therefore,

a = 1

b = 2

c = 1

d = 2

The elements cycle through the atmosphere is biogeochemical cycle. In atmosphere different types of cycle are revolving around.

The biogeochemical cycle is refer to the exchange of substances between biotic and abiotic sources.  

It can also be defined as the process by which a chemical material circulates through Earth's biotic and abiotic regions.

There are six types of biogeochemical cycle.

Thus, the elements cycle through the atmosphere is biogeochemical cycle. In atmosphere different types of cycle are revolving around.

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Decreasing the temperature in the reaction vessel keep this reaction from shifting to form more of the product.

As we know that rate of reaction is directly proportional to the concentration of the reactant.

If we increase the concentration of H2 then the rate of reaction increases. So, we keep it constant. Therefore this option is wrong.

By removing the H₂O from the reaction vessel as it almost make no change in the reaction. This can be pursuited the reaction in which product again converted into product.

By increasing the temperature we increases the rate of reaction and equilibrium shift in the forward direction.

Thus, we concluded that by decreasing the temperature in the reaction vessel keep this reaction from shifting to form more of the product.

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Answer:

Your coefficients (the numbers in front of the molecule) will be the following from left to right.

1. 1 - 2 - 1 - 2

2. 2 - 1 - 2 - 2 - 1

3. 2 - 4 - 1

4. 2 - 4 - 3

5. 2 - 2 - 2 - 1

6. 1 - 1 - 1

7. 2 - 1 - 2

8. 3 - 1 - 2 - 3

9. 3 - 1 - 2 - 3

10. 2 - 1 - 1 - 1

Explanation:

To balance this equations first count how many times an element is on each side and then see what needs to be changed in order to balance them.

V=kn   is an expression of Avogadro's law where temperature and pressure are constant.

Avogadro's law is a gas law  which states that the total number of atoms or molecules  has a direct proportion  to the volume occupied by a gas at a constant temperature and pressure.

It is closely related to ideal gas equation  as it links temperature, pressure, volume and the amount of substance.It is given as, V∝n,

The straight line graph of volume versus moles is a straight line passing through the origin which implies that zero moles of gas occupy zero volume.The empirical relation of Avogadro's law is  derived from the kinetic theory of gases by taking into consideration the assumptions of an ideal gas.

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The temperature of a substance is directly related to its kinetic energy. Because kinetic energy is the energy a substance has because of its molecules being in motion, as a substance absorbs heat its molecules move faster, thereby increasing the substance's kinetic energy.

From this we can get that 50 grams of water at 100 °C will have highest average kinetic energy then 25 grams of water at 50 °C will have slightly less kinetic energy then 200 grams of water at 10 °C and then 100 grams of water at -20 °C

This implies that RMS speed and temperature also have a relationship. The average kinetic energy (K) is determined by multiplying the RMS speed (vrms) by the square of the mass (m) of each gas molecule.

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Answer:I need help with the last two questions pls my chemistry teacher not good

Explanation:

I need help with the last two questions pls my chemistry teacher not good

Answer

The moles of Mg that reacted = 0.005 moles

The moles of H₂SO₄ that reacted = 0.005 moles.

Justification: The mole ratio from the balanced equation is 1 : 1 and since the moles of H₂SO₄ (0.005 mol is less than 0.020571898 mol of Mg) is the limiting reactant, it determines when the reaction goes into completion.

Explanation

Given:

Mass of magnesium that reacts = 0.50 g

The volume of sulfuric acid that reacts = 25 cm³

Molarity of sulfuric acid that reacts = 0.20 moldm⁻³

What to find:

The number of moles of magnesium and sulfuric acid that reacted.

Step-by-step solution:

Step 1: Write the balanced chemical equation for the reaction.

Mg + H₂SO₄ → H₂ + MgSO₄

Step 2: Convert the mass of Mg and molarity of H₂SO₄ to moles.

The mass of Mg can be converted to moles using the mole formula:

25 cm³ of 0.20 moldm⁻³ of H₂SO₄ can be converted to moles using the formula for molarity:

Step 3: Calculate the number of moles of magnesium and sulfuric acid that reacted.

From step 2: moles of Mg = 0.020571898 mol, moles of H₂SO₄ = 0.005 mol

Using the mole ratio of Mg and H₂SO₄ from the balanced equation in step 1, that 1 mol Mg = 1 mol H₂SO₄

Therefore, the moles of Mg that reacted will be 0.005 moles, and the moles of H₂SO₄ that reacted will be 0.005 moles.

Justification: The mole ratio from the balanced equation is 1 : 1 and since the moles of H₂SO₄ (0.005 mol is less than 0.020571898 mol of Mg) is the limiting reactant, it determines when the reaction goes into completion.

(a) Therefore the limiting reagent is N2.

(b) The kilograms of excess reagent left = 0.5709 kg.

(c) % Yield = 89.475 %.

Given reaction is

N2(g) + 3H2(g) ------> 2NH3(g)

mass of N2=18.2 kg=18.2 x 103 g (Since 1 kg=1000 g)

Molar mass of N2=28.0134 g/mol

Moles of N2=mass/molar

mass = (18.2 x 103 g)/(28.0134 g/mol) = 649.689 mol.

the mass of H2 = 4.5 kg = 4.5 x 103 g = 4500 g

The molar mass of H2 = 2.01588 g/mol

Moles of H2 = (4.5 x 103 g )/(2.01588 g/mol) = 2232.276 mol.

As per the balanced equation, the mole ratio between N2:H2 = 1:3.

But here N2:H2 = 649.689: 2232.276  = 1:3.436

That means H2 is in excess.

(a) Therefore the limiting reagent is N2.

(b) The actual moles of H2 required = 3 x mol of N2 used = 3 x 649.689 mol = 1949.067 mol.

Mass of H2 required = moles x molar mass = 1949.067 mol x 2.01588 g/mol = 3929.085 g.

The excess mass of H2 present = 4500 g - 3929.085 g = 570.91 g = 0.5709 kg.

The kilograms of excess reagent left = 0.5709 kg.

(c) The theoretical yield of NH3 = 2x moles of N2 used = 2 x 649.689 mol = 1299.378 mol.

The molar mass of NH3 = 17.03052 g/mol

Therefore theoretical yield of NH3 =moles x molar mass = 1299.378 mol x 17.03052 g/mol = 22129.08 g

Theoretical yield of NH3 =22.129 kg

Given the experimental yield of NH3 = 19.8 kg.

Therefore,

% Yield = (Experimental yield)/(Theoretical yield ) x 100

% Yield=(19.8 kg/22.129 kg) x 100=89.475 %.

% Yield=89.475 %.

Reagent or analytical reagent is a substance or compound that is added to a system to produce or test a chemical reaction as it occurs. The terms reactant and reactant are not often used interchangeably, but a reactant defines a substance that is used up in  a chemical reaction.

H2 (hydrogen gas) and O2 (oxygen gas) are reactants in the reaction that forms liquid water: 2 H2(g) + O2(g) → 2 H2O(l).

Note that mass is conserved in this equation. There are four hydrogen atoms and two oxygen atoms on the original and multiplicative sides of the equation.

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A given element must have the same number of protons as neutrons and electrons, this is not a requirement. No other element has an atom with two protons besides helium, which has two protons in every atom.

An electrical force keeps electrons in their shells. An atom's protons and electrons are drawn to one another. They are both electrically charged. Electrons have a negative charge (-), while protons have a positive charge (+).

Electrons are present outside the atom's nucleus, in contrast to protons and neutrons, which are contained inside the nucleus at its center. Negative electrons are drawn to the positive nucleus because the electric charges of opposite polarity attract one another.

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The complete question is -

Does a given element always have the same number of each particle? Why or why not? Using periodic table, give some specific examples.

Answer:

you know how when you jump, you don't go flying away, that's because of a thing called gravity, it keeps everyone from floating into the sky.

Answer: if you were jumping on the bed you don’t just fly off right?! That’s crazy! Gravity keeps us from falling of the earth!

Explanation: