1. Which of the following elements are metals, nonmetals and metalloids?
As, Xe, Fe, Li, B, Cl, Ba, P, I, Si.

• According to the balanced equation, we have :

4 Fe(s) + 3 O2(g) → 2 Fe2O3(s)

4 x 55.85g of Fe reacts with 3 x 32g of Oxygen

Given 17.86 g of Ion, we want to find out how much oxygen will be required in this instance .

• So :

M.mass Fe: 4* 55.85 = 223.4

M.mass O2 : 3* 32 = 96

we can rearrange by :

223.4 → 96

17.86 → x .....(cross multiply )

223.4x = 96* 17.86

x = (96 *17.86) / 234.4

x = 7.314

• Therefore mass of oxygen required = 7.3g ,



Answer:

The student changed too many variables.

The strong base to be in equilibrium refers to shifting towards the left side of the reaction and far away from the right side i.e option 1

What do you understand by equilibrium?

A system is at an equilibrium when all of its external forces are in balance.

Generally, In any acid-base reaction, the equilibrium will favor that side of reaction which moves the proton towards the stronger base.

Let us consider the given reaction

HCl (acid)  +  NaOH (strong base)   NaCl  +  H20

As per the reaction, equilibrium will shift towards the left side as it involves the abstraction of the proton by the base.

Hence, the answer is option 1 first which means the position of equilibrium lies far to right.

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The change in enthalpy of the gas mixture during the reaction is - 95 kj.

The formula for the change in internal energy is given by:

ΔU = ΔH + W

ΔU = the change in inter energy = -181 kj ( decreased)

ΔH = the change in enthalpy

W = work done =  -86 kj

substituting the values in the formula we get :

ΔU = ΔH + W

- 181 kj = ΔH  - 86 kj

ΔH = -181 kj + 86  kj

ΔH = - 95 kj

Measurements show that the energy of a mixture of gaseous reactants decreases by 181.kj during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that -86.kj of work is done on the mixture during the reaction. The change in enthalpy of the gas mixture during the reaction is - 95 kj.

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Answer

Explanation

Note that a mole of any substance has 6.02 x 10²³ atoms of that substance.

Let x represent the mole of magnesium present in 5.01 x 10²² atoms of magnesium.

Therefore,

Cross multiply, and divide both sides by 6.02 x 10²³ atoms to get x

The sinking of the ocean crust back into the mantle when it meets continental crust is referred to as subduction , and this process occurs at the ocean trenches.

This is referred to as a geological process which occurs when there is collision between two tectonic plates in the earth in which one of the plate sinks into the mantle underneath the other plate.

During this process of subduction, the ocean crust sinks back into the mantle when it meets continental crust and it occurs mainly at the ocean trenches thereby making the options provided the correct choice.

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Scientific notation is the way that scientists handle large numbers and small numbers. For example, instead of writing 0.000 000 0056, they write 5.6 × 10⁻⁹.

We can think of 5.6 × 10⁻⁹ as the product of two numbers: 5.6 (the digits) and 10⁻⁹ (the power of 10).

Here are some examples of scientific notation.

1000 = 1 × 10³; 7354 = 7.354 × 10³

100 = 1 × 10²; 482 = 4.82 × 10²

10 = 1 × 10¹; 89 = 8.9 × 10¹

1 = 1 × 10⁰; 6 = 6 × 10⁰

1/10 = 0.1 = 1 × 10⁻¹; 0.32 = 3.2 × 10⁻¹

1/100 = 0.01 = 1 × 10⁻²; 0.053 = 5.3 × 10⁻²

1/1000 = 0.001 = 1 × 10⁻³; 0.0078 = 7.8 × 10⁻³

The exponent of 10 is the number of places we must shift the decimal point to get the scientific notation.

Each place the decimal moves to the left increases the exponent by 1.

Each place the decimal point moves to the right decreases the exponent by 1.

EXAMPLE:

Write the following numbers in scientific notation: 1001;

6 926 300 000; -392; 0.000 000 13; -0.0038

Solution:

1.001 × 10³; 6.9263 × 10⁹; -3.92 × 10²; 1.3 × 10⁻⁷; -3.8 × 10⁻³

Hope this helps!

Answer:

dwn

Explanation:

Oxalic acid solution is a primary standard because it is highly pure, stable and does not change its concentration with environmental factors. > Coming to option B, Sodium thiosulphate, it is a secondary standard reagent. Sodium thiosulphate is also called hypo.

You can see that NO₂⁻ has an oxidation number of -1 and V³⁺ has an oxidation number of +3.

When we state the chemical formula of these compounds, we need to have that the algebraic sum of the oxidation numbers must be zero. In this case, we have that the sum is -1 + 3 = 2, it is incorrect because we need to have the result of zero.

For this problem, we can multiply three times NO₂⁻ obtaining that the oxidation number is -3, so the algebraic sum would be: (-1)(3) + 3 = -3 + 3 = 0. This means that the chemical formula will have three times NO₂⁻ bonded with V³⁺ and it would be:

1) The solubility of the ions are;

lead II ions = 6.96 * 10^-4 M

iodide ions = 3.48 * 10^-4 M

2) The Ksp of silver chromate is 8.98 * 10^-22

We know that the Ksp has to do with the equilibrium constant that shows the extent to which a substance dissolves in water. We can see that the equation of the dissolution can be written for each of the reactants.

a) [tex]PbI2 (s) --- > Pb^{2+} (aq) + 2I^{-} (aq)[/tex]

Now we can see that the Ksp is obtained from;

Ksp = [[tex]Pb^{2+}[/tex]] [2[tex]I^{-}[/tex]]^2

Let the solubility be x

Ksp = 4x^3

x = ∛ 1.35 x 10^-9/4

x = 6.96 * 10^-4 M

Hence;

Concentration of lead II ions = 6.96 * 10^-4 M

Concentration of iodide ions =  6.96 * 10^-4 /2 = 3.48 * 10^-4 M

b) In order to obtain the solubility product of the silver chromate solution;

Let the solubility of each of the ions be x

We can see that;

Ksp = [3x]^3 [x]

Ksp = 3x^4

Ksp = 3(4.16 x 10^-6)^4

Ksp = 8.98 * 10^-22

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Every substance has a specific temperature range at which it changes from one phase (solid, liquid, or gas) to another.

Measure the melting, boiling, and/or sublimation points of several substances using a realistic melting point device to see what these phase changes appear like on a tiny scale.

Make assumptions about the relative potency of the forces binding these compounds together based on the transition points.

By placing a small amount of an organic solid into a capillary tube, attaching it to the thermometer's stem in the centre of a heating bath, and gradually heating the bath, one can ascertain the temperature at which melting starts and ends.

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Potassium oxide is an ionic compound formed by combining potassium and oxygen. It carries the chemical formula K2O.

So, this is expected product from the reaction of potassium with oxygen because of the following:

To get the net charge of the compound equal to zero, we need to satisfy the equation K2O. So that's the answer.

This alkyl halide can be prepared by electrophilic addition of HBr to 2 different alkenes because of alkenes undergo hydrogenation in presence of acid and base when HBr can added to the different alkyl 3-methyl-hex-2-ene, 3-methyl-hex-3-ene and 3-methylene hexane

Hydrogenation is the chemical reaction in which molecular hydrogen and another compound and element usually in presence of catalyst such as nickel, palladium or platinum and this process is commonly employed to reduce or saturated organic compound

Addition of hydrogen and halogen to the double bond or triple bond based on markovnikov rule of addition and when HBr is added to CH3- CH=CH2 then Br is added to CH group and H is added to the CH₂ group of the alkene and if the reaction is carried in the presence of any peroxide then reverse addition is taking place

Then different alkyl structure such as 3-methyl-hex-2-ene, 3-methyl-hex-3-ene and 3-methylene hexane and image is given below

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The amount of gold that can be produced from 213.46g AuPO₄ is equal to 143.7g.

A mole is a standard unit that can be used to determine the huge number of quantities of ions,  atoms, molecules, or other particular particles. The mass of the 1 mole of any element is known as atomic mass (in grams) and the mass of one mole of any compound is called molar mass.

The number of units in one mole was found to be approximately 6.023 × 10 ²³  also called Avogadro’s constant.

Given, the mass of the AuPO₄  = 213.46 g

The molar mass of the AuPO₄ = 197 + 31 + 4(16) = 292 g/mol

The number of moles of the AuPO₄  = 213/292 = 0.729 mol

If the mole of AuPO₄  will produce one mole of the Au.

Then 0.729 mol of the AuPO₄ will produce Au = 0.729 mol

The mass of the Au (in grams) = 0.729 ×197 = 143.7 g/mol

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Answer:

0.286 M

Explanation:

This is a great example of a practice problem that requires you to use the formula for dilution calculations.

To make it more interesting, let's assume that you're not familiar with that problem.

The most important thing to remember about a dilution is the the number of moles of solute must remain constant.

That is, the number of moles of solute present in the initial solution must be equal to the number of moles of solute present in the diluted solution.

Since molarity is defined as moles of solute per liter of solution, keeping the number of moles of solute constant allows you to decrease concentration by increasing the total volume of the solution.

195 ml of 0.355 ml NaCl is added to a 0.500 ml volumetric flask and the flask is filled with water. The [ Na⁺ ] concentration in the diluted solution is 138.45 M

Concentration is calculated by dividing a constituent's abundance by the mixture's total volume. Mass concentration, molar concentration, number concentration, and volume concentration are four different categories of mathematical description.

Molarity is the number of moles of solute per liter of solution and mole fraction is the proportion of solute moles to all other moles of substances present. Parts per thousand grams, mass percentage, the ratio of the solute's mass to the solution's mass multiplied by 100.

M₁ V₁ = M₂ V₂

0.355 × 195 = M₂ × 0.500

M₂ = 0.355 × 195 ÷ 0.500

138.45 M

Thus, The [ Na⁺ ] concentration in the diluted solution is 138.45 M

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Answer:B

Explanation:

The equilibrium constant relates the concentrations of the products and reactants in the chemical equilibrium. To calculate it we can apply the following equation.

For the reaction: aA + bB ---> cC + dD

Equlibrium constant (Ke) will be:

The letters in square brackets refer to the concentration raised to the respective coefficient. Now we replace the known values:

So, the equilibrium constant (Ke) will be 3.2M

Answer

a. Increasing the air pressure on the solution.

Explanation

Oxidation takes place at the anode. Reduction takes place at the cathode. Oxidation takes place on the left and recution takes place on the right.

The standard cell notation for an electrolytic cell with alumium and gold electrodes:

To determine which metal undergoes oxidation and which undergoes reduction we use the standard cell potentetial of the metals. Au is the stronger oxidising agent of the two and so it is likely to undergo reduction and so the Al will undergo oxidation.

Answer: A

Answer:

E, C, A, 90, 5, D, B, D, D, D and B, A C and E, A, E

Explanation:

1. is correct, it is E
2. is C, not D. D is when the liquid is freezing/when the solid is melting.
3. the answer is A. B is when the gas is condensing or when the liquid is boiling.
4. 90 temperature units. This is the boiling point. Technically the substance can still condense below this point until 5 temperature units, or D, but ignore that.
5. 5 temperature units.
6. D, this is where the solid and liquids exchange states (ie melting/freezing)
7. B, this is where boiling and condensing occurs
8. Crystallisation is a fancy word for freezing. The melting and freezing points are the same, so D
9. D. Fusion means freezing.
10. D and B.
11. A, C, and E
12. A has the highest temperature and the highest kinetic and potential energy
13. E has the lowest kinetic and potential energy

Answer:

Moles of Ca3(PO4)2 = 0.455 M * 0.125 L = 0.0569 mol

1 Mole of Ca3(PO4)2 = 3 moles of Ca2+ ions

Thus, moles of Ca2+ ion = 3 * 0.0569 = 0.1707 ~ 0.171 moles

The number of moles of ions in a solution can be calculated using the molarity and volume of the solution. The number of moles of Ca ²⁺ ions contained in 0.125 L of 0.455 M solution of Ca₃ (PO₄) ₂ is 0.0170 moles.

Molarity is a term used to represent the concentration of the solution. Mathematically it is the ratio of number of moles of solute to the volume of solution in liters.

The molarity of the calcium phosphate solution is given 0.455 M  and its volume is 0.125 L. Thus, the no.of moles of calcium phosphate in the solution is calculated as follows:

no.of moles of Ca₃ (PO₄) ₂  = molarity × volume

                                             = 0.455 M  × 0.125 L

                                             = 0.0568 moles.

It is clear from the formula that one mole of calcium phosphate contains 3 moles of Ca ²⁺ ions. Therefore,  the number of moles of calcium ions in 0.0568 moles of calcium phosphate is calculated as follows:

No. of moles of Ca ²⁺ ions  = 0.0568 × 3

                                            = 0.0170 moles.

Hence the number if moles of calcium ions in 0.125 L of 0.455 M calcium phosphate is 0.0170 moles.

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Answer:

6 N to the left, or -6 N
unbalanced

Explanation:

The forces are two 3 N forces. The forces are additive, so 3+3 = 6, so the answer is 6 N to the left.
Since the net force isn't 0, the forces are unbalanced (aka the block will move since there is a force pushing the block)

Answer:

Copper(I) bromide

Explanation:

Copper has oxidation numbers of +1 or +2

Bromide has a common charge of -1

This can be called Copper I bromide more precisely .or somewhat redudanately Copper mono bromide.

An older form of naming would be Cupous Bromide. Indicating a +1 charge on Copper. Cupric Bromide would be CuBr2 indicating a + 2 charge.

Answer:

Species. A population is a group of plants or animals of the same species that live in an area.

Answer:A

Explanation:because i did the test

Component Q is more powerful in explaining a scientific phenomenon because peer conformation and support are characteristics of a theory.

Scientific phenomena are events that can be witnessed in the natural and artificial worlds that make people wonder and pose questions. A theory is a logical interpretation or explanation of a phenomenon or set of occurrences. For instance, the theory of evolution through natural selection is a hypothesis because it explains the variety of life on earth.

In addition to offering accurate explanations or interpretations, theories also serve additional objectives. Here, we examine three additional goals of theories: the organizing of well-understood phenomena, the forecasting of outcomes in novel circumstances, and the development of fresh lines of inquiry.

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The pH of a solution that is 0.67 M in sodium fluoride and 0.43 M in hydrofluoric acid is 8.53

The pH of a solution is the negative logarithm of the hydrogen ion concentration of the solution.

Mathematically:

The pH of the given solution is calculated as follows:

Ka of HF = 7.2 * 10⁻⁴

Also, Kw = Ka * Kb

Kw = 1.0 * 10⁻¹⁴

Kb = 1.0 * 10⁻¹⁴ / 7.2 * 10⁻⁴

Kb = 1.39 x 10⁻¹¹

The [OH¯] is calculated using the Kb expression:

Kb = [OH⁻] * [H⁺] / [HA}

[OH⁻] = [H⁺] = x

Kb = x² / (0.83 - x)

Assuming x is negligible, the denominator = 0.83

x = √(1.39 x 10⁻¹¹ * 0.83)

x = 3.39 * 10⁻⁶

pOH = -log (3.39 * 10⁻⁶)

pOH = 5.47

pH = 14 - 5.47

pH = 8.53

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Combination. Option E is correct.

Given the chemical reaction between carbon and oxygen expressed as:

From the equation, you can see that carbn combines with oxygen atom to produce carbonmonoxide. This type of reaction is known as the combination reaction since it involves the reaction of two elements to produce a compound (carbon monoxide)

Based on the explanations above, we can concude that the reaction of carbon with oxygen to produce carbon monoxide is an example of a combination reaction.

Answer:

a. Aluminum nitride

Explanation:

The compound AlN is a salt made up of Al and N.

Analyzing the oxidation states of each element, we can see that Aluminum acts with 3+ (because it has only one oxidation state), so Nitrogen need to interact with an oxidation state of 3-, for the molecule to be neutral.

Due to the nitrogen acts with 3- the name of the salt will be Aluminum nitride.

1) Check if the chemical reaction is balanced.

2) Moles of NaOH in the reaction.

3) Moles of neutralized acid.

4) Molarity of H2SO4