Atoms disappear during a chemical change true or false

Relative and average atomic mass both describe properties of an element related to its different isotopes. Out of these two Relative atomic mas is more accurate. Therefore, the average atomic mass of copper is 63.55amu.

Mass defines the quantity of a substance. It is measured in gram or kilogram. Average mass is the mass of atoms of an element that are isotopes. It can be calculated by multiplying mass of a isotope to natural abundance of that isotope.

Average atomic mass = (mass of first isotope× percent abundance of first isotope)+(mass of second isotope× percent abundance of second isotope)

Substituting the given values, we get

Average atomic mass=(  62.96  amu × 70.5% )+(64.96 amu ×29.5% )

Average atomic mass=55.58+12.27

Average atomic mass=63.55amu

Therefore, the average atomic mass of copper is 63.55amu.

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The molecular weight of the ascorbic acid (vitamin C), given that 0.9 g of the acid was dissolved in 95 g of water is 170.7 g/mol

We'll begin by obtaining the mole of the ascorbic acid in the solution. Details below

Mole = Molality × mass of water (in kg)

Mole of ascorbic acid = 0.0555 × 0.095

Mole of ascorbic acid = 0.0052725 mole

Finally, we shall determine the molar mass of the ascorbic acid. Details below

Molar mass = mass / mole

Molar mass of ascorbic acid = 0.9 / 0.0052725

Molar mass of ascorbic acid = 170.7 g/mol

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A + BC → AB + C "single replacement reaction" while ammonia synthesis is a "synthesis reaction".

A single replacement reaction is a reaction by which one element replaces an/another element in a compound.

It can be represented generically as: A + B-C → A-C + B This will most often occur if A is more reactive than B, thus giving a more stable product.

A chemical reaction known as a synthesis occurs when two or more simple chemicals combine to create a more complex result. The result is always a chemical, while the reactants can be either elements or other compounds.

Example: ammonia synthesis,

N₂ + 3H₂ ⇄ 2NH₃

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Answer:

Explanation:

The velocity of electrons can be calculated using the equation v = h / (mλ), where h is Planck's constant (6.63 x 10^-34 Js), m is the mass of the electron, and λ is the wavelength of the radiation.

For sodium, the electron energy is given as Φ = 4.41 × 10–19 J. To find the velocity of the electrons, we first need to convert the energy into wavelength using the equation λ = hc / Φ, where c is the speed of light (3 x 10^8 m/s).

So, for sodium:

λ = hc / Φ = 6.63 x 10^-34 x 3 x 10^8 / 4.41 x 10^-19

λ = 290 nm.

And then using the velocity equation,

v = h / (mλ) = 6.63 x 10^-34 / (9.11 x 10^-31 x (290 x 10^-9))

For potassium, the electron energy is given as Φ = 3.68 × 10–19 J, and the wavelength can be calculated in the same way as for sodium:

λ = hc / Φ = 6.63 x 10^-34 x 3 x 10^8 / 3.68 x 10^-19

λ = 290 nm.

And then using the velocity equation,

v = h / (mλ) = 6.63 x 10^-34 / (9.11 x 10^-31 x (290 x 10^-9))

Note: m is the mass of an electron, which is 9.11 x 10^-31 kg.

So, both the velocity of the electrons from sodium and potassium would be the same, given that they are both exposed to the same wavelength radiation of 290 nm.

Answer:The velocity of electrons from sodium and potassium can be calculated using the equation E=hf, where E is the energy of the electron, h is Planck's constant and f is the frequency of the radiation.

From the equation E=hf, f can be calculated using the wavelength of the radiation:

f = c/λ

where c is the speed of light.

Then, using E=hf and the values for E (Φ) for sodium and potassium, the velocity of the electrons can be calculated using the equation:

v = sqrt(2E/m)

where m is the mass of the electron.

Explanation:

The velocity of electrons from sodium and potassium can be calculated using the equation E=hf, where E is the energy of the electron, h is Planck's constant and f is the frequency of the radiation.

From the equation E=hf, f can be calculated using the wavelength of the radiation:

f = c/λ

where c is the speed of light.

Then, using E=hf and the values for E (Φ) for sodium and potassium, the velocity of the electrons can be calculated using the equation:

v = sqrt(2E/m)

where m is the mass of the electron.

Explanation:

The atomic mass of gallium for this location can be calculated using the following formula:

Atomic mass = (69^Ga abundance x 69^Ga mass) + (71^Ga abundance x 71^Ga mass)

Plugging in the values:

Atomic mass = (0.6011 x 68.7200 amu) + (0.3989 x 70.9200 amu) = 41.4762 amu + 28.2957 amu = 69.7719 amu

Therefore, the atomic mass of gallium for this location is 69.77 amu.

When a cracker dissolves in your mouth, then this is a chemical change. A chemical reactions is an atomic rearrangement-based chemical process.

An alteration of one or more compounds as one or maybe more new and distinct substances is referred to as a chemical change or chemical reaction. In other terms, a chemical reactions is an atomic rearrangement-based chemical process.

A chemical change normally cannot be reversed unless through additional chemical processes, although a physical change may frequently be done so. The power of the system changes when a chemical shift takes place. When a cracker dissolves in your mouth, then this is a chemical change.

Therefore, when a cracker dissolves in your mouth, then this is a chemical change.

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In the PhET activity, "Properties of Gases", when pressure is kept the same and heat the volume increases. Therefore, option D is correct.

Charles' law states that if the pressure remains constant, the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature.

This law states that a gas's volume and temperature have a direct relationship: as temperature rises, volume rises when pressure remains constant. When a gas is heated, the kinetic energy of the particles increases, causing the gas to expand.

Thus, option D is correct.

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Mole is one of the International System of Units' seven foundation units, in reality (SI). Units are created when preexisting ones are insufficient. Therefore, 11.2moles of NO[tex]_2[/tex] is produced.

Simply put, a mole is a measuring unit. It's one of the International System of Units' seven foundation units, in reality (SI). Units are created when preexisting ones are insufficient.

At the same time that using official figures of atoms, molecules, or ions would be unclear, chemical reactions frequently occur at low concentrations where using grams would've been inappropriate. Therefore, the mole was created by scientists to fill the gap between extremely small and extremely huge quantities.

2N[tex]_2[/tex]O[tex]_5[/tex](g)→4NO[tex]_2[/tex](g)+O[tex]_2[/tex](g)

moles of N[tex]_2[/tex]O[tex]_5[/tex] = 5.6 mol

the mole ratio between N[tex]_2[/tex]O[tex]_5[/tex] and NO[tex]_2[/tex] is 1:2

moles of NO[tex]_2[/tex] = 2× 5.6=11.2moles

Therefore, 11.2moles of NO[tex]_2[/tex] is produced.

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The amount, in grams of KCl that will be produced, would be 5.00 grams.

KClO3 decomposes when heated to produce KCl and O2 according to the following equation:

[tex]2KClO_3 -- > 2KCl + 3O_2[/tex]

Equivalent mole of 5.0 g KClO3 = 5/122.5 = 0.0408 mol

Since the mole ratio of KClO3 to KCl is 1:1, the mole of KCl formed will also be 0.0408 mol.

Mass of 0.0408 mol KCl = 0.0408 x 122.55

                                        = 5.00 grams

In other words, the mass of KCl that would be produced is 5.00 grams.

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The heat of solution for 10.5 g of potassium perchlorate dissolved in 113.8 mL of water is approximately -83.99 kJ/10.5 g.

The heat of solution is described as the enthalpy change associated with the dissolution of a substance in a solvent at constant pressure resulting in infinite dilution.

For 10.5 g of potassium perchlorate dissolved in 113.8 mL of water, the amount of heat released can be estimated as follows:

-599 kJ/mol x (10.5 g / 138.55 g/mol) = -44.31 kJ

-548 kJ/mol x (10.5 g / 138.55 g/mol) = -39.68 kJ

The heat of solution for potassium perchlorate will then be calculated as the sum of the lattice energy and heat of hydration which gives us that

Heat of solution = -44.31 kJ + -39.68 kJ = -83.99 kJ/10.5 g

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Ca(C2H3O2)2 has 30.41% carbon by volume, according to calculations.

By dividing the atomic mass of the element by the molar mass of the compound, then by 100%, one can get the percentage of the element in a compound.

The percentage form of the mixture is obtained by multiplying this ratio by 100.

By dividing the atomic mass of the element by the molar mass of the compound, then by 100%, one can get the percentage of the element in a compound.

Atomic mass of C divided by the molar mass of Ca(C2H3O2) yields the percentage of carbon.

₂ × 100%

Ca(C2H3O2)2 has an atomic mass of 40 plus (24 plus 3 plus 32).

2 = 158g/mol \s % C = 12.01(4)/158 × 100 \s % C = 30.41%.

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Photosynthesis is the process in which plants use sunlight, water, and carbon dioxide to make oxygen and energy in the form of sugar. During each step of photosynthesis that is Sunlight absorption, Light-dependent reactions, Light-independent reactions explain in below description.

Sunlight absorption: Special pigments in photosynthetic cells absorb light energy. Plant pigment molecules absorb light with wavelengths ranging from 400 nm to 700 nm. This wavelength range is known as photosynthetically active radiation (PAR).

Light-dependent reactions: Light energy is used in light-dependent reactions to create two molecules required for the next stage of photosynthesis: the energy storage molecule ATP and the reduced electron carrier NADPH. Light reactions occur in the thylakoid membranes of chloroplast organelles in plants.

Light-independent reactions: Photosynthesis's light-independent reactions occur within the stroma. It contains enzymes that, in collaboration with ATP and NADPH, "fix" carbon from carbon dioxide into molecules that can be used to make glucose. The stroma also stores the chloroplast's own genetic material.

Thus, These are the steps of photosynthesis.

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The liquid in Titan's lake is believed to be composed of liquid methane and ethane, which are thought to be supplied by geological processes such as cryovolcanism and seepage from the surrounding terrain. Over time, the liquid in Titan's lake can evaporate, change due to geological or meteorological processes, or be affected by the changing seasons on the moon.

Lewis structures are useful for visualizing both ionic and covalent bonds. In the idealized ionic bond.

In covalent bonding, nonmetallic elements part electrons so that both elements can have a full valence shell. Covalent bonds can be meant with electron dot formulas. These are often mentioned as Lewis structures and are a little different than the electron dot formulas used to constitute ionic bonds.

Lewis one atom gives up an electron to the other, forming positive and negative ions. The state for bonds is that the total structure charge is zero and that each atom must have a gentle gas electron configuration. In covalent combination, the Lewis Dot Structures must show

So we can conclude that Using Lewis structure Symbols to relate Covalent Bonding.

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One mole or 12 g of carbon reacts with one of oxygen molecule weighs 32 g will produce one mole of carbon dioxide. One mole of carbon dioxide weighs 44 g.

Carbon dioxide is an inorganic gas formed by the covalent bonding between carbon and oxygen gas. Carbon dioxide is an essential gas to maintain the living atmosphere in earth.

The balanced chemical equation of the reaction between oxygen gas and carbon is given below:

[tex]\rm C+O_{2} \rightarrow CO_{2}[/tex]

As per this equation, one mole of carbon reacts with one mole of oxygen gas:

Atomic mass of carbon = 12g

molecular mass of oxygen = 32 g

then molar mass of carbon dioxide = 32+ 12 = 44 h=g.

Therefore, 44 g of carbon dioxide is produced in this reaction.

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Newton's first law states that unless acted on by an unbalanced force, an object will remain at rest or move at a constant speed in a straight line. To move the book on your desk, Newton's first law requires an unbalanced force.

The First Law of Motion of Newton (Inertia) Unless acted on by an unbalanced force, an object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line.

When an unbalanced force acts on an object, the object's motion changes. The object's speed or direction may change. Friction is a force that opposes motion or the tendency for motion between two objects in contact.

Thus, an object will remain at rest or move at a constant speed in a straight line.

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Equations are balanced using the idea of chemical reactions. to ensure that the reactant side and product side are in equilibrium the steps are below

Balancing chemical equations means making sure that the same number of atoms of each element are present on both sides of the equation. Here are the steps to balance a chemical equation:

It's important to keep in mind that the coefficients should be kept in their lowest whole number ratios, and you can use fractional coefficients if necessary. If the equation is already balanced, no further action needs to be taken.

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The intermolecular force present in butter is London dispersion forces. In kerosene, covalent bonding between carbon and hydrogen atoms are present.

Intermolecular forces are force exerted between two molecules which can be of attraction or repulsion. The intermolecular force of attraction make the atoms binded in a compound or molecule.

In butter, the hydrocarbon molecules exerts a London dispersion forces between two non-polar molecules. In kerosene, the hydrocarbon molecules are bound by covalent bonding between carbon atoms.

In ethanol, the OH group make it possible to form hydrogen bonds between ethanol molecules. In the case of calcium fluoride, dipole, dipole forces exists. Since the compound is ionic and have a permanent dipole moment.

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False, using changes in tempo and dynamics can make a musical cliché more effective. Hence, option C is correct.

Tempo in a music refers to pace of the music especially in high pitch sound waves. The most common unit of measurement for tempo is beats per minute (BPM), which is just the quantity of beats that may be captured in a minute at a certain pace.

A musical segment or composition is slower when the beats per minute  is lower than when the BPM is greater. While a higher BPM is more likely to make the listener feel excited, a lower BPM is more likely to have a calming and/or sad effect on the listener.

Changing dynamics is some more effective way to make musical cliché. Hence, option C is correct.

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The number of molecules for 229 mg

The atomic mass from

Molecular mass is the sum of all the atomic mass in the compound.

According to Stoichiometry to calculate the number of moles of a compound

n = m ÷ M

X = n × L

Calculating the number of molecules

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The ion concentration of 0.05 M [tex]CaCl_2[/tex] would be 0.05 mol Ca ions and 0.1 mol Cl ions respectively.

[tex]CaCl_2[/tex] contains two ions according to the following equations:

[tex]CaCl_2 -- > Ca^{2+} + 2Cl^-[/tex]

1 mole           1 mole   2 moles

0.05 M CaCl2 contains 0.05 moles of the solute in 1 liter of the solution. Thus, the equivalent mole of Ca ion would be 0.05 moles while that of Cl ion would be 0.10 mole (0.05x2).

Concentration of Ca ions = 0.05 moles

Concentration of Cl ions = 0.05 x 2 = 0.010 moles

In other words, the ion concentrations of 0.05 M CaCl2 would be 0.05 moles of Ca ions and 0.10 moles of Cl ions.

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The osmotic pressure of the protein solution is given 3.54 torr or 0.004 atm. Then, the molar mass of the protein is 7222 g/mol.

The pressure required to stop the flow or diffusion of  solvent molecules through a semipermeable membrane is called osmotic pressure. The osmotic pressure is represented as π and is related to the pressure, volume and number of moles as follows:

π  = n RT

given π = 3.54 torr = 0.004 atm

volume v = 23 ml  = 0.023 L

temperature = 27 °C = 300 K

R = 0.082 L atm/ K mol

then, n = π V/RT

n = 0.004 atm ×0.023 L /(0.082 L atm/ K mol × 300 K)

  = 3.69× 10⁻⁹.

weight of the protein sample = 26.75 mg = 0.026 g

then, molar mass =   0.026 g/ 3.69× 10⁻⁹mol  = 7222 g/mol

Therefore, the molar mass of the protein sample is 7222 g/mol.

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4.4 a. The metal that the main part of the garden fork has been made from is iron. The correct option is B

b. The chemical name for rust is hydrated iron (iii) oxide

c. One way of preventing the fork from rusting is by painting the fork.

4.5 Based on the given equations;

a. the equation that produces a metal oxide is equation D.

b. the equation that is a neutralization reaction is equation B.

c. the equation that is a burning reaction is equation A.

The complete equation for the given equations are:

d. sodium + water → sodium hydroxide + hydrogen

e copper carbonate + sulfuric acid → copper sulfate + carbon dioxide + water

f. sulfur + oxygen → sulfur dioxide

Rust is an iron oxide, a typically reddish-brown oxide created when iron and oxygen react catalytically with moisture from the air or water.

Iron(III) oxide-hydroxide and hydrated iron(III) oxides make up rust, which is often linked to the corrosion of refined iron.

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The original concentration of the Pb(NO₃)₂ solution in mol/L would be 0.00036 moles / 0.64 L = 0.0000056 mol/L = 0.056 mM (rounded to 3 significant figures).

We must do a mass-to-moles conversion to ascertain the Pb(NO3)2 solution's initial concentration. The following equation describes the precipitation reaction between Pb(NO₃)₂  and H₂SO₄:

Pb(NO₃)₂ + H₂SO₄ -> PbSO₄ + 2HNO₃

PbSO₄ has a molar mass of 303.2 g/mol. 

Therefore, 0.00036 moles of PbSO₄ are equal to 0.109 g of PbSO₄  divided by 303.2 g/mol. 

Therefore, 0.00036 moles of PbSO₄ are equal to 0.109 g of PbSO₄  divided by 303.2 g/mol.  Since the ratio of Pb(NO₃)₂  to PbSO4 in the reaction is 1:1, we can infer that the initial solution included the same number of moles of Pb(NO₃)₂  

Since the ratio of Pb(NO₃)₂  to PbSO₄  in the reaction is 1:1, we can infer that the initial solution included the same number of moles of Pb(NO₃)₂   The Pb(NO₃)₂  solution's initial concentration would therefore be 0.00036 moles / 0.64 L = 0.0000056 mol/L = 0.056 mM. (rounded to 3 significant figures).

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The number of moles of hydrogen gas produced from 1.2 g of water is 0.06 moles. Then, the partial pressure of hydrogen gas is 4.9 atm.

The partial pressure of a gas in a mixture is the contribution of the gas to the total pressure of the mixture.

The molar mass of water = 18 g/mol

mass = 1.2 g

number of moles  = 1.2/18 =0.06 moles.

now the total pressure p = nRT/v

V = 0.20 L

T = 30°C =303 K

then  p = (0.06 mol × 0.082 L atm/ K mol × 303 K) / 0.20 L = 7.4 atm.

Now, 2 moles of water gives 2 moles of hydrogen gas and one mole of oxygen. Then 0.06 moles of water gives 0.06 moles of hydrogen and 0.03 moles of oxygen.

Then, mole fraction of hydrogen = 0.06/(0.03 + 0.03) = 0.66.

Partial pressure of hydrogen = total pressure × mole fraction

= 0.66 × 7.4 atm = 4.9 atm.

Therefore, the partial pressure of hydrogen gas is 4.9 atm.

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a. 225.0 has 4 significant figures.

b. 1000.0 has 4 significant figures.

c. 0.0003210 has 6 significant figures.

d. 0.0067 has 4 significant figures.

e. 1,000,000 has 7 significant figures.

f. 2.00001 has 6 significant figures.

Question 2

a. 15.9994 rounded to three significant figures is 16.0.

b. 1.0080 rounded to three significant figures is 1.01.

c. 0.6654 rounded to three significant figures is 0.665.

d. 4885 rounded to three significant figures is 4885.

e. 87,550 rounded to three significant figures is 88,000.

f. 0.027225 rounded to three significant figures is 0.0272.

Question 3

a. 77.981 x 2.33 = 181.081 (rounded to 3 significant figures)

b. 4 x 0.0665 = 0.266 (rounded to 3 significant figures)

c. 17,344,900 + 23.1 = 17,344,923.1 (rounded to 7 significant figures)

d. 9.80 - 4.762 = 5.038 (rounded to 3 significant figures)

e. 3.9 x 6.05 x 420 = 8,595.89 (rounded to 2 decimal places)

f. 14.1 / 5 = 2.82 (rounded to 2 decimal places)

g. 1001 + 16.23 = 1017.23 (rounded to 4 significant figures)

h. 424.5 + 2.8461 = 427.3461 (rounded to 4 decimal places)

i. 9.9 - 9.54 = 0.36 (rounded to 2 decimal places)

j. 7.3778 / 0.000265 = 27,864.345 (rounded to 3 decimal places)

k. (24.358) x (6.4) = 156.3712 (rounded to 4 decimal places)

(48.6) x (0.6959) = 33.88594 (rounded to 5 decimal places)

Significant figures of a number in positional notation are described as digits in the number that are reliable and necessary to indicate the quantity of something.

Decimal places on the other hand are described as positions of the digits to the right of a decimal point. Rounding numbers to decimal places is shortening a decimal number to a given degree of accuracy.

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The balanced chemical equation for the reaction is:

N2SO4 + 2NaOH → Na2SO4 + 2H2O

From the equation, we can see that for every 1 molecule of sodium sulfate (Na2SO4), 2 molecules of water (H2O) are produced. Therefore, to find the number of molecules of water produced, we need to determine the number of molecules of sodium sulfate produced in the reaction.

To do this, we need to use the molar mass of sodium sulfate and Avogadro's number. The molar mass of sodium sulfate is 142.04 g/mol, and Avogadro's number is 6.022 x 10^23.

The number of molecules of sodium sulfate produced in the reaction can be calculated as follows:

(2.0 g) / (142.04 g/mol) = 0.01405 mol

And the number of molecules of water produced can be calculated as follows:

0.01405 mol x 2 molecules/mol = 0.0281 x 6.022 x 10^23 molecules/mol = 1.69 x 10^23 molecules

Round 1.69 to 2.0 and your answer is  2.0 x 1023 molecules

Answer :Hydrophobicity is measured in terms of the contact angle of the water drops to the surface of textiles

Explanation:

The mass of sulfur in a sample of CaSO4 with a mass of 67.0 g would be 15.73 grams.

11.5 grams of CaSO4 contains 3.39 grams of Ca and 5.41 g of O.

Mass of sulfur = 11.5 - (3.39 + 5.41) = 2.7 grams

11.5 grams of CaSO4 contains 2.7 grams of sulfur. The mass of sulfur in 67.0 grams of CaSO4 can be estimated as:

11.5 grams CaSO4 = 2.7 grams S

67.0 grams CaSO4  = 67.0 x 2.7/11.5

                                 = 15.73 grams

In other words, if 11.5 grams of CaSO4 contains 2.7 grams of S, then 67.0 grams will contain 15.73 grams of sulfur.

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