A chemistry teacher carried out several demonstrations, and students recorded their observations. For one of the demonstrations, a student concluded that a physical change took place, but not a chemical change. Which of the following observations could the student have made of the results of the demonstration?

Answer:

[tex]Ni^{2+}[/tex]

Explanation:

From the equation attached , [tex]Ni^{2+}[/tex] is reduced. This is because reduction is equivalent to decrease in the oxidation number. In the equation , The oxidation number of Ni is reduced from +2 to 0.

NB, The oxidation number of a neutral atom is zero

Answer:Energy is coverted into a waterfall

Explanation:Answer:A waterfall is a sudden drop in a river as it flows over a rock cliff. This happens when the river passes from a layer of hard rock to a layer of softer rock, and the water erodes away the softer rock. A watershed is the term given to the land that drains water into a particular stream, lake, or river.

Answer:

w = 0.00098 N

Explanation:

Given data:

Acceleration = 9.80 m/s²

Mass of honey = 0.0001 Kg

weight = ?

Solution:

Formula:

w = mg

w = weight

m = mass

g = acceleration due to gravity

Now we will put the values in formula:

w = 0.0001 Kg × 9.80 m/s²

w = 0.00098 N

Answer:

If the electronegativity difference between bonded atoms are too much high ionic bonds are formed if the electronegativity diference is 0.4 or less than 0.4 non polar covalnet bond formed the difference greater than 0.4 polar covalent bond formed.

Explanation:

Ionic bond:

It is the bond which is formed by the transfer of electron from one atom to the atom of another element.  

Both bonded atoms have very large electronegativity difference. The atom with large electronegativity value accept the electron from other with smaller value of electronegativity.

For example:

Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion.

Covalent bond:

It is formed by the sharing of electron pair between bonded atoms.  

The atom with larger electronegativity attract the electron pair more towards it self and becomes partial negative while the other atom becomes partial positive.

For example:

In water the electronegativity of oxygen is 3.44 and hydrogen is 2.2. That's why electron pair attracted more towards oxygen, thus oxygen becomes partial negative and hydrogen becomes partial positive.

Answer:

Here's what I get  

Explanation:

In a single replacement reaction, one element must displace another element from its compound.

Thus, we must consider the reactivity series, because an element lower down in the series cannot replace one that is above it.

In a double replacement reaction, the cations change partners with the anions. All we need consider are the solubilities of the new cation-anion partners.

In a single replacement reaction, it is mandatory that one element displaces the other according to their reactivity on the reactivity series.

On the other hand, In a double- displacement reaction; the cations just exchange anions and vice versa.

An example of a single displacement reaction is;

An example of a double displacement reaction is;

As such, there's no preference in double displacement reactions as ions are swapped.

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Answer:

ethene is a limiting reagent here

Answer:

Density is a physical property but volume isn’t because density is intensive property but volume is extensive property.    

Explanation:

EXTENSIVE PROPERTY- A property of matter like volume and mass which depends on the amount of being measured is called extensive property.

INTENSIVE PROPERTY- A property of matter like colour and density which does not depend on the amount of the substance present is called intensive property.

new SUBSTANCES are fomed

Answer:

Energy Conservation is the effort made to reduce the consumption of energy by using less of an energy service.

Energy conservation refers to both the physical principle that energy cannot be created or destroyed and the practical approach of reducing energy consumption and improving efficiency. It involves both changes in individual behaviors and technological advancements to lower energy use and waste.

Energy Conservation Defined

Energy conservation is an important concept in Physics that refers to two key ideas. Firstly, it encompasses the principle that energy cannot be created or destroyed, only transformed from one form to another. This is known as the Conservation of Energy principle. Secondly, in a more practical sense, energy conservation relates to methods and strategies aimed at reducing energy waste and enhancing efficiency. This includes behaviors like turning off lights when not in use, driving efficiently, and using energy-efficient appliances.

Conservation of energy ensures that we reduce our consumption, either by decreasing activities that use energy or by improving the efficiency with which we perform tasks. An example of increasing efficiency would be implementing technological advancements, such as better-insulated homes, which require less energy for heating.

In summary, energy conservation serves both as a fundamental physical law and as a practical approach to manage and reduce energy usage in our daily lives. This dual understanding facilitates the development of sustainable practices and the creation of more efficient technologies, aimed at minimizing our ecological footprint.

Answer:

Are native to the reefs and rocky crevices of the Indo-Pacific, although they've found their way to warm ocean habitats worldwide.

Explanation:

Answer:

Ph= -log10[H+}

Explanation:

Ph+ -log 10(6.7*10-5)≅ 4

Answer:

4.17

Explanation:

Answer: its mostly reflected.

Answer:

So whilst Phosphorus is an anion, it will usually combine with Iron or Aluminium and act like a cation. The more fine colloids in the soil (such as clay) then the greater the ability of the soil to bind cations.

Explanation:

Answer:

The explanation is given below

Explanation:

Dalton was the first who putted forward the theory about atom. he describe the properties of atoms of the element. Dalton based his theory on the law of conservation of mass and the law of constant composition.

His theory has 5 basic postulates and these five principals are still true.

1. Dalton stated that all matter composed of atoms are very small in size. these smallest unit of matter (atom) take part in chemical reaction.

2. All the atoms of an element are similar in shape, size, and other properties but different from the atoms of other element.

3. This theory states all matter is made up of atoms and atom can not be created nor destroy.

4. Law of constant composition:

According to this: atoms of different elements combine in a simple, fixed and whole number ratio to form compound.

5. Atoms the element can combine in more than one ratio and form two or more compounds.

The atomic theory of Dalton explained many things.

Other models are its modification and explanation. Dalton was the first who recognize difference between atom of an element compound.

Although there are some discrepancies to explain other points but these 5 points are still workable and true.

The principle that still holds true from Dalton's atomic theory is the law of conservation of matter.

Even though new models were discovered after Dalton created his five principles, one principle that still holds true is the idea that atoms are neither created nor destroyed during a chemical change, which is known as the law of conservation of matter. This means that the total mass of matter present in a chemical reaction remains constant.

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Answer:

B) Cell Membrane

Explanation:

A) Chloroplasts are NOT in all cells, A is incorrect

C) Centrioles are for cell division, C is not correct

D) Cell walls are NOT in all cells, D is not correct

B) the cell membrane is responsible for materials traveling into and out of the cells to maintain homeostasis

Answer:

27.7  × 10²³ atoms

Explanation:

Given data:

Number of moles of Potassium = 4.6 mol

Number of atoms = ?

Solution:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

1.008 g of hydrogen = 1 mole = 6.022 × 10²³ atoms of hydrogen

For 4.6 moles of K:

One mole = 6.022 × 10²³ atoms

4.6 mol × 6.022 × 10²³ atoms= 27.7  × 10²³ atoms

Answer:

1597.959 g  

Explanation:

Given Data:

Amount of Cr₂(SO₄)₃ = 450 g

Amount of potassium phosphate K₃PO₄ = in Excess

grams of potassium sulfate K₂SO₄= ?

Solution

The Reaction will be

                 Cr₂(SO₄)₃ + 2K₃PO₄  ----------> 3K₂SO₄ + 2CrPO₄

Information that we have from reaction

                Cr₂(SO₄)₃ + 2K₃PO₄  ----------> 3K₂SO₄ + 2CrPO₄

                    1 mol          2 mol                   3 mol

we come to know from the above reaction that

1 mole of chromium(iii) sulfate (Cr₂(SO₄)₃) react with 2 mole of potassium phosphate (K₃PO₄) to produce 3 mole of K₂SO₄

We also know that

molar mass of Cr₂(SO₄)₃ = 147 g/mol

molar mass of K₃PO₄ = 212 g/mol

molar mass of K₂SO₄ = 174 g/mol

if we represent mole in grams then

      Cr₂(SO₄)₃             +       2K₃PO₄          ----------> 3K₂SO₄ + 2CrPO₄

       1 mol (147 g/mol)         2 mol  (212 g/mol)      3 mol  (174g/mol)

So, Now we have the following details

          Cr₂(SO₄)₃  +  2K₃PO₄          ----------> 3K₂SO₄ + 2CrPO₄

              147 g         424 g                           522 g

So,

we come to know that 147 g of Cr₂(SO₄)₃ combine with 424 g of 2K₃PO₄ produce  522 g of K₂SO₄

So now we calculate that how many grams of potassium sulfate will be produced

Apply unity formula

              147 g of  Cr₂(SO₄)₃  ≅ 522 g of K₂SO₄

              450 g of  Cr₂(SO₄)₃  ≅ ? g of K₂SO₄

by doing cross multiplication

g of K₂SO₄ =522 g x 450 g / 147 g

g of K₂SO₄ =  1597.959 g

So the write answer is  1597.959 g  

***Note: By calculation it is obvious that the correct answer is  1597.959 g  

You may find bellow the answers and the balanced chemical reactions.

Explanation:

2) The chemical reaction is:

2 Na + I₂ → 2 NaI

Na - sodium

I - iodine

In this reaction there are 2 reactants and 1 product.

The reaction is balanced.

3) The chemical reaction is:

N₂ + O₂ → 2 N₂O

N - nitrogen

O - oxygen

In this reaction there are 2 reactants and 1 product.

The reaction is not balanced, the balanced reaction is:

2 N₂ + O₂ → 2 N₂O

4) The chemical reaction is:

N₂ + 3 H₂ → 2 NH₃

N - nitrogen

H - hydrogen

In this reaction there are 2 reactants and 1 product.

The reaction is balanced.

5) The chemical reaction is:

2 KI + Cl₂ → 2 KCl + I₂

K - potassium

I - iodine

Cl - chlorine

In this reaction there are 2 reactants and 2 products.

The reaction is balanced.

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balanced chemical reactions

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Answer:

Na, valency 1.

Explanation:

Na -sodium.

This element is in the 1A group, so it has 1 electron on the last (valent) level.

So, only 1 electron can participate in forming chemical bond, and therefore the valency of Na is 1.

Final answer:

Sodium (Na) is the element in group IA and the 3rd period, and it has a valency of 1 because it has one valence electron that it can lose to form a +1 cation.

Explanation:

The element that lies in group IA and the 3rd period of the periodic table is Sodium (Na). The valency of sodium is 1, which refers to its ability to combine with other atoms and ions. This valency is because sodium falls in group IA, where the elements have one valence electron that they can lose to form a cation with a +1 charge. The group number for elements in groups 1 and 2 directly correspond to their valences, which is why sodium has a valency of 1.

Answer:

B

Explanation:

She stopped for 4 minutes

She was decreasing in speed

Answer:

The correct answer it 8 m/s north

Explanation:

My test answers

Both are considered mixtures - that is, they are made up of two or more pure substances. ... A heterogeneous mixture appears to be made of different substances. A solution appears the same throughout. In the fluid phase (gas or liquid, or any combination of those) a solution is transparent (thought not colourless).

Final answer:

Heterogeneous mixtures have non-uniform composition and can be differentiated by eye, while solutions have uniform composition throughout and no settling occurs.

Explanation:

A heterogeneous mixture is a combination of two or more substances in which the composition is not uniform throughout the sample, and the individual substances can be differentiated by eye. Examples of heterogeneous mixtures include trail mix, salad, and blood. On the other hand, a solution is a type of homogeneous mixture where the composition is uniform throughout and no settling occurs. Solutions can be colored but are transparent, and the dissolved species are molecules or ions. Examples of solutions include air, simple syrup, and seawater.,

Answer:

The resulting NaCl solution  has a concentration of 0.4732 M

Explanation:

Concentration is the ratio of  amount of solute present  in a solution to  the amount of  solvent or total solution. Morality  is the commonly used unit of concentration.

[tex]Concentration=\frac{(\text{Moles of solute})}{(\text{Volume of solution})}[/tex]

Since we are given with same NaCl solution, we have

[tex]\frac{(M_1 V_1+M_2 V_2)}{(V_1+V_2 ) }[/tex]....................(1)

Where  

[tex]M_1= 0.690 m[/tex]

[tex]V_1= 309 ml[/tex]

[tex]M_2= 0.330 m[/tex]

[tex]V_2= 467 ml[/tex]

Now substituting the values in equation in (1)

=>[tex]\frac{( (0.690\times 309 )+(0.330\times 467))}{(309+467) }[/tex]

=>[tex]\frac{ (213.21\times 154.11)}{776}[/tex]

=>[tex]\frac{367.32}{776}[/tex]

=>0.4732 M

The resulting concentration when 309 ml of a 0.690 m NaCl solution is mixed with 467 ml of a 0.330 m NaCl solution is 0.473 M.

To find out the resulting concentration of NaCl when two solutions of different concentrations and volumes are mixed, we need to determine the total amount of NaCl and the total volume of the solution. The mole of NaCl in a solution can be determined by multiplying the molarity of the solution by its volume.

For the first solution, the number of moles of NaCl = volume (L) × molarity (M) = 0.309 L × 0.690 mol/L = 0.2133 mol

For the second solution, the number of moles of NaCl = volume (L) × molarity (M) = 0.467 L × 0.330 mol/L = 0.154 mol

The total moles of NaCl = 0.2133 mol + 0.154 mol = 0.367 mol

The total volume = volume of first solution + volume of second solution = 0.309 L + 0.467 L = 0.776 L

Finally, the resulting concentration = total moles / total volume = 0.367 mol / 0.776 L = 0.473 M

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Answer:

20 Liters

Explanation:

If the pressure is supposed to be constant, one of Charles - Gay Lussac's laws can be used to solve the exercise. His statement says that "the volume of the gas is directly proportional to its temperature at constant pressure", mathematically it would be:

[tex]\frac{V1}{T1} = \frac{V2}{T2}[/tex]

Considering T₁ = 50 ° C; V₁ = 10.0 L; and T₂ = 100 ° C, we can calculate the volume V₂ Clearing it from the equation and replacing the values to perform the calculation:

V2= (V1 x T2) / T1  = (10.0 L x  100°C)  / 50 °C = 20 L

Therefore, the gas at 100 ° C will occupy a volume of 20.0 L.

To find the volume a gas will occupy at a higher temperature at constant pressure, use Charles's Law formula V1/T1 = V2/T2. After converting Celsius to Kelvin, solving the problem indicates the new volume at 100 °C would be approximately 11.54 L.

The question involves calculating the change in volume of a gas when it is subjected to a change in temperature, knowing that the pressure is held constant. This is a problem that can be addressed using Charles's Law, which states that the volume of a gas is directly proportional to its temperature on a Kelvin scale. To solve the problem, you must first convert the temperatures from Celsius to Kelvin by adding 273.15 to each temperature. Once you have the temperatures in Kelvin, you can use the formula V1/T1 = V2/T2, where V1 is the initial volume, T1 is the initial temperature, V2 is the final volume, and T2 is the final temperature.

In this case, the initial temperature is 50 °C (323.15 K) and the final temperature is 100 °C (373.15 K). The initial volume is 10.0 L, and you are solving for the final volume.

Using the formula:

V2 = V1 * (T2/T1) = 10.0 L * (373.15 K / 323.15 K) = 11.54 L

This is the volume the gas will occupy at 100 °C at constant pressure.

Answer: Why do all the members of a group have similar properties? They have similar properties, because they share similar amounts of electrons in their outer shell, valence electrons! This means they will only be able to interact with other elements with those electrons so they often show similar properties.

Explanation:

Answer: This is because their valence electrons are located in the S - orbital

Explanation:

This is because their valence electrons are located in the S - orbital.

Answer:

wood shaving

Explanation:

fire would spread faster

hope that helps

Answer:

The pile of wood will catch fire more easily because the shavings of wood will be heated faster as compared to the hunk of wood.

Explanation:

The reasons for wood shaving will be burnt faster than hunk of wood are:

Therefore, the wood shavings will be burnt faster than the hunk of wood because of the smaller surface area and the combustion reaction will be faster than hunk of wood.

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Answer:

Explanation:

Torr:

Torr is the measure of pressure produced by one mmHg equal to the 1/760 of standard pressure used to the pressure of vacuum system.

Millimeter mercury mmHg:

It is the manometric pressure unit. It is defined as, the pressure exerted by column of mercury one millimeter high. it is represented by mmHg.

Torr to mmHg conversion:

Both are equal to each other.

1 torr = 1 mmHg

Torr to atm:

Torr is converted into atm by dividing the torr value 760.

mmHg to atm.

mmHg is converted into atm by dividing the torr value 760.

Kilopascal:

The kilopascal is the unit of pressure. It is represented by KPa.

it is the pressure generated by 10 g mass of substance on area of 1 cm².

There are 1000 pascal in one kilopasca.

one atm = 101.325 KPa

one atm = 101325 Pa

atm can be converted into KPa by multiplying the given atm value with 101.325.

For example:

4.1 atm × 101.325  kpa/ 1 atm

415.432 atm. kpa / 1atm

415.432 kpa

Kpa to atm:

415.432 kpa/101.325  kpa × 1 atm

4.1 × 1 atm

4.1 atm

Pressure units such as pascals (Pa), kilopascals (kPa), atmospheres (atm), millimeters of mercury (mm Hg), and torr are commonly used in chemistry. The standard conversion equivalencies enable accurate measurement when switching between these units. For example, to convert torr to atm, divide by 760, and to convert psi to kPa, multiply by 6.895.

Understanding pressure conversions is important in chemistry when dealing with gases. The most common units of pressure are pascals (Pa), kilopascals (kPa), atmospheres (atm), millimeters of mercury (mm Hg), and torr. The relations between these units are as follows:

1 bar = 100,000 Pa = 1.01325 atm

To convert these units, use the specified equivalencies. For example, to convert from torr to atm, use the following formula:

Pressure in atm = Pressure in torr / 760

To convert 32 psi to kPa: 32 psi * 6.895 = 220.64 kPa (as 1 psi = 6.895 kPa)

To convert 6.50 millibars to atm: 6.50 m bars / 1013.25 = 0.00642 atm (since 1 bar = 1.01325 atm, and 1 mbar = 0.001 bar)

It's essential to use these conversion factors correctly to obtain accurate pressure values in different units.

Answer:

Electrons, Atomic Number

Explanation:

The total number of electrons is different for each and every element of the periodic table.

It is known as the atomic number of an element.

Mendeleev's Periodic Table's principle:

The properties of the elements is a periodic function of their atomic mass.

But, this was true only for the lighter elements.

So, the principle of the Long Form of the Periodic Table is:

The properties of the elements is a periodic function of their atomic numbers.