A cup of gold colored metal bed was measured to have a mask for 25 g. By water displacement, the volume of the bed was calculated to be 40.0 mL. Given the following densities, identify the metal. Gold equals 19.3 g/milliliters copper equals 8.86 g/milliliters bronze equals 9.87 g/milliliters

Answer:

[OH⁻] = 0.000324619M

pH = 10.51

[CN⁻] = 5.175x10⁻³M

Explanation:

Full question says:

Calculate the OH- concentration and pH of a 5.5×10-3M aqueous solution of sodium cyanide, NaCN. Finally, calculate the CN- concentration.

Ka (HCN) = 4.9×10-10

Sodium cyanide, is in equilibrium with water as follows:

NaCN(aq) + H₂O(l) ⇄ HCN(aq) + OH⁻(aq)

Where Kb (Kb = Kw / Ka = 1x10⁻¹⁴ / 4.9x10⁻¹⁰ = 2.04x10⁻⁵) is:

2.04x10⁻⁵ = [HCN] [OH⁻] / [NaCN]

In equilibrium, ann amount of HCN and OH⁻ is produced = X and the molarity of NaCN is: 5.5x10⁻³M - X

Replacing in Kb expression:

2.04x10⁻⁵ = [X] [X] / [5.5x10⁻³M - X]

1.12x10⁻⁷- 2.04x10⁻⁵X = X²

1.12x10⁻⁷- 2.04x10⁻⁵X - X² = 0

Solving for X:

X = -0.0003 → False solution. There is no negative concentrations

X = 0.000324619

As [OH⁻] = X.

pOH = -log [OH⁻]

pOH = 3.489

pH = 14 -pOH

And as molarity of NaCN = [CN⁻] = 5.5x10⁻³M - X

Answer:

135 KJ.

Explanation:

The following data were obtained from the question:

Mass of ethanol, C₂H₅OH = 143.45 g

Heat of vaporisation, ∆Hvap = 43.3 kJ/mol

Heat required (Q) =.?

Next, we shall determine the number of mole in 143.45 g of ethanol (C₂H₅OH). This is can be obtained as follow:

Mass of ethanol, C₂H₅OH = 143.45 g

Molar mass of ethanol, C₂H₅OH = (12×2) + (1×5) + 16 + 1

= 24 + 5 + 16 + 1

= 46 g/mol

Mole of ethanol, C₂H₅OH =?

Mole = mass /Molar mass

Mole of ethanol, C₂H₅OH = 143.45/46

Mole of ethanol, C₂H₅OH = 3.118 moles

Finally, we shall determine the heat required to vaporize the ethanol, C₂H₅OH as follow:

Heat of vaporisation, ∆Hvap = 43.3 kJ/mol

Mole of ethanol, C₂H₅OH (n) = 3.118 moles

Heat required (Q) =.?

Q = n•∆Hvap

Q = 3.118 × 43.3

Q = 135 KJ

Therefore, the heat required is 135 KJ

Answer:

The theoretical yield (in grams) of soap is 514.9 grams

Explanation:

Please see the attachments below

Answer:

Source, processing and distribution are the components of water system.

Explanation:

There are three parts of water system i. e. the source, the processing and distribution. Water is extracted from a source such as underground water, lake or river etc. After extraction this water is transported to the processing unit where it can be purified and after purification it is distributed to all places where it is needed. Potential energy is a form of energy that flows through this water system because the water is extracted from a depth and we know that depth and height refers to potential energy.

Answer:

d) 2, 4-Dimethylpentane

Explanation:

2, 4-Dimethylpentane is the c_7 compound that gives 3 signals in the broadband proton decoupled ¹³C spectrum.

This compound is classified as an alkane and it's chemical formula is [(CH3C)2CH]2CH2. It is a hydrocarbon that has no odor. When it is combined with other gas compounds it gives high octane fuel.

Answer:

Making models

Explanation:

Classifying is the grouping together of items that are alike in some way. Answer: Making models involves creating rep- resentations of complex objects or processes.

Explanation:

5) Le Chatelier's principle says, when in a reversible reaction any of the concentration or temperature or pressure are changed, then the equilibrium shifts such a way to nullify the changes occurred. (hope you get it)

R ======= P

if concentration of reactant R is increased then eqm shifts towards the one with lower concentration ,that is product P.

forward direction is favoured.

if the above's reaction is endothermic, that is temp of product is low. So increasing temperature in such case reaction goes towards product.

forward direction is favoured.

If reaction is exothermic ,temp of reactant is more. So increasing temperature in such case, reaction goes towards reactants.

forward direction is favoured

........ plz brainliest my answer I definitely write you the complete explanation asap!

Answer:

The ozone layer is a shield district of Earth's stratosphere that ingests a large portion of the Sun's bright radiation. It contains a high grouping of ozone (). It contains atoms of oxygen that keep the environment from hurtful beams that are available in space and boundless by the sun, for instance, bright beams.  

Scientists from the Copernicus Atmosphere Monitoring Service confirm that the 2021 Antarctic ozone hole has almost reached its end, following a season with a considerably large and prolonged ozone hole. Its closure will occur only a few days earlier than in 2020, which was the longest-lived since 1979.

It closed on 23 December, the third latest date after 1999 and 2020. The extent and longevity of the 2021 ozone hole can be explained by very cold temperatures in the stratosphere and a very stable polar vortex. This video shows the evolution of the 2021 Antarctic ozone hole.

Learn more about The Ozone Hole at

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#SPJ2

Answer:

[tex]60 cm^{3}[/tex]

Explanation:

volume=lwh

v=3*5*4

v=[tex]60 cm^{3}[/tex]

Answer: Yes

Explanation:

On the periodic table, you can find the element symbol, name, atomic number, and atomic mass. Just knowing the atomic mass and atomic number can give you the amount of neutrons. The atomic number states the amount of protons. The atomic mass is proton+neutron. Knowing this, you can subtract the atomic mass by the atomic number to get neutron.

Example: Carbon

Atomic number: 6

Atomic mass: 12.011 or 12

12-6=6                                                   [Atomic mass - Atomic number]

There are 6 neutrons in Carbon.

Answer:

10.64

Explanation:

Let's consider the basic reaction of cyclohexamine, C₆H₁₁NH₂.

C₆H₁₁NH₂(aq) + H₂O(l) ⇄ C₆H₁₁NH₃⁺(aq) + OH⁻     pKb = 3.36

C₆H₁₁NH₃⁺ is its conjugate acid, since it donates H⁺ to form C₆H₁₁NH₂. C₆H₁₁NH₃⁺ acid reaction is as follows:

C₆H₁₁NH₃⁺(aq) + H₂O(l) ⇄ C₆H₁₁NH₂(aq) + H₃O⁺(aq)   pKa

We can find the pKa of C₆H₁₁NH₃⁺ using the following expression.

pKa + pKb = 14.00

pKa = 14.00 - pKb = 14.00 - 3.36 = 10.64

The pKa of conjugate acid of cyclohexamine has been 10.64.

The pKa has been acid dissociation constant, and has been describing the hydrogen ion concentration in the sample.

The pKb has been the base dissociation constant and has been describing the hydroxide ion concentration in the sample.

The sum of pKa and pKb has been found to be 14.

[tex]\rm pKa \;+\;pKb=14[/tex]

The pKb of cyclohexamine has been 3.36. The pKa of conjugate acid in the sample has been given by substituting the values as:

[tex]\rm pKa\;+\;3.36=14\\pKa=14\;-\;3.36\\pKa=10.64[/tex]

The pKa of conjugate acid of cyclohexamine has been 10.64.

For more information about pKa and pKb, refer to the link:

https://brainly.com/question/12639696

Answer:

A. Protium

B. Deutrium

C. Tritium

Explanation:

A hydrogen isotope with one proton:

Protium

A hydrogen isotope with two protons:

Deutrium

A hydrogen isotope with protons:

Tritium

Hope this helped ;) ❤❤❤

The correct answer is D. Grocery stores that sell legumes

Explanation:

One of the main points this claim proposes is that metabolism can be improved by consuming legumes, this is expressed in "incorporating legumes such as lentils and chickpeas... boosts metabolism." In this context, if this is proven as true through an argumentative text or speech, it is likely many people want to increase their intake of legumes because a better metabolism has multiple benefits for health. Moreover, increased intake of legumes means an increase in the sale of legumes and higher profits for stores selling legumes. This means the claim might benefit grocery stores that sell legumens (option D.)

Answer:

A) It must be negative

Explanation:

A spontaneous reaction in Chemistry is that which is proceeding in a particular direction without the intervention of any external effect. As a spontaneous reaction proceeds (which can be relatively slow), free energy ΔG, which is the available energy for work, is released.

Gibbs free energy, ΔG, is released during a spontaneous process and hence the ΔG is negative because the reactants have more free energy than the products, hence, no energy input is needed for the reaction to proceed forward but rather an energy output. This is what makes a negative ΔG depict a spontaneous reaction.

Answer:

Explanation:

molecular weight of gold = 197

converting 10.2 g into moles

no of moles = 10.2 / 197

= .0518 moles

one  mole of any element contains 6.02 x 10²³ number of atoms

.0518 moles will contain 6.02 x .0518 x 10²³ atoms of gold

= .311 x 10²³ no of atoms of gold .

= 3.11 x 10²² no of atoms of gold

Answer:

Nitrogen

Explanation:

Hello,

In this case, for the given reaction we first need to assign the oxidation state for each species in the chemical reaction:

[tex]Sn ^{2+}(aq) + (N^{-3}H^+_4)^ +(aq) \rightarrow Sn^0(s) + (N^{5+}O_3^{2-})^ -(aq)[/tex]

In such a way, since the tin is decreasing its oxidation state it is being reduced whereas the nitrogen is being oxidized as its oxidation state is being increased from -3 to +5.

Best regards.

The element which is oxidized in the redox reaction shown below is Nitrogen.

Sn²⁺(aq) + NH⁴⁺(aq) → Sn(s) + NO₃⁻(aq)

In this scenario, the oxidation state of Sn changed from +2 to 0 while the

oxidation state of Nitrogen changed from -3 to +5.  The Nitrogen(N) present

in the equation experienced an increase in the oxidation state which means

it was oxidized.

The Tin(Sn) on the other hand experienced a reduction in the oxidation state

which means it was reduced.

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The question is incomplete, the complete question is;

With all of this data in hand, we can now set up our reaction. To begin we are going to use 0.7 g of (35)-2.2-dibromo-3,4-dimethylpentane. Question #7: Using the molecular weight (258 g/mol) determine the amount of mmol of (3S)-2,2,- dibromo-3,4-dimethylpentane required. Round to the tenths place

Answer:

2.70 mmols

Explanation:

Given that;

Mass of (3S)-2,2,- dibromo-3,4-dimethylpentane = 0.7 g

Molar mass of (3S)-2,2,- dibromo-3,4-dimethylpentane = 258 g/mol

From,

Number of moles = mass/molar mass

Number of moles of (3S)-2,2,- dibromo-3,4-dimethylpentane = 0.7g/258 g/mol = 2.7 ×10^-3 moles

Therefore;

Number of moles of (3S)-2,2,- dibromo-3,4-dimethylpentane = 2.70 mmols

Answer:

1 mol of electron is exchanged. The mol of electrons that is released by the iron, is gained by the silver.

Explanation:

We need to determine the half reactions:

Ag⁺ → Ag

These is the reduction reaction, where Silver decreases the oxidation state. It gained 1 mol of e⁻

Fe²⁺ → Fe³⁺

In this case, iron increases the oxidation state, from +2 to +3. It has released 1 mol of electrons. This is the oxidation reaction.

The complete redox is:

Ag⁺ + 1e⁻ → Ag

Fe²⁺ → Fe³⁺ + 1e⁻

Ag⁺(aq) + 1e⁻ + Fe²⁺(aq) ⇌ Ag(s) + Fe³⁺(aq) + 1e⁻

The electrons will be cancelled.

In the redox reaction Ag⁺(aq) + Fe²⁺(aq) ⇌ Ag(s) + Fe³⁺(aq),

1 mole of electrons is exchanged.

Let's consider the following balanced redox reaction.

Ag⁺(aq) + Fe²⁺(aq) ⇌ Ag(s) + Fe³⁺(aq).

We can identify both half-reactions.

We can conclude that:

In the redox reaction Ag⁺(aq) + Fe²⁺(aq) ⇌ Ag(s) + Fe³⁺(aq),

1 mole of electrons is exchanged.

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Answer:

-15.5 kJ/mol

Explanation:

2A ⇄ 2B + C

[tex]$ K = \frac{[C][B]^2}{[A]^2} $[/tex]

   = [tex]$ \frac{(0.69)(0.49)^2}{0.88^2} $[/tex]

  = 0.21

T = [tex]$ 43.9^{\circ} $[/tex]C

   = (273 + 43.9) K  =  316.9 K

[tex]$ \Delta G^{\circ} = -19.4 $[/tex] kJ/mol

R = 8.314 J/k-mol  =  0.008314 kJ/k-mol

[tex]$ \Delta G = \Delta G^{\circ} - RT \ln K $[/tex]

     [tex]$ =-19.4 - 0.008314 \times 316.9 \ln (0.21) $[/tex]

     = -15.5 kJ/ mol

Answer:

1.5 moles of CO₂ are produced

Explanation:

Based on the chemical equation:

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O -The reaction of the question is wrong-

5 moles of oxygen reacts per mole of propane, C₃H₈, to produce 3 moles of CO₂ and 4 moles of water.

If 2.5 moles of oxygen react and, 5 moles of oxygen produce 3 moles of CO₂, moles of CO₂ produced are:

2.5 moles O₂ * (3 moles CO₂ / 5 moles O₂) =

Answer: The possible structure for this compound is 2,4-dimethyl-3-pentanone

Explanation:

It should be noted that, If the 1H NMR spectrum of a compound with formula C7H14O gives a doublet at 9.2 ppm. The possible structure for this compound is 2,4-dimethyl-3-pentanone

Answer:

A. 2

B. 3

C. 4

Explanation:

Please see attached photo for explanation.

Answer:

0.168mL of the 1.0M KI solution must be added

Explanation:

The PbI₂ is in equilibrium with water as follows:

PbI₂ ⇄ Pb²⁺ + 2I⁻

Where Ksp is:

Ksp = 1.4x10⁻⁸ = [Pb²⁺] / [I⁻]²

As molarity of Pb²⁺ is 0.11M:

1.4x10⁻⁸ = [0.11M] / [I⁻]²

1.27x10⁻⁷ = [I⁻]²

3.57x10⁻⁴M = [I⁻]

Thus, to precipitate all Pb²⁺ you need to add 3,57x10⁻⁴M of I⁻. As volume of the solution is 470.0mL = 0.47L, you need to add:

0.47L * (3,57x10⁻⁴moles / L) = 1.68x10⁻⁴ moles of I⁻ = Moles of KI.

That comes from the 1.0M KI. You need to add:

1.68x10⁻⁴ moles of KI * (L / 1.0 mol) = 1.68x10⁻⁴L =

Answer:

1) HCl reagent was added in excess

Explanation:

The equation of the reaction is given as;

Zn + HCl --> ZnCl2 + H2

From the stoichiometry;

1 mol of Zn reacts with 1 mol of HCl

In 2g of Zn;

mass = 2

Molar mass = 65.38g/mol

Number of moles = Mass/ Molar mass = 2 / 65.38 = 0.03059 mol

In 10ml of HCl;

the number of moles is: moles = Concentration * Volume =  (10 moles/L) (0.0100 L) = 0.10 moles

Comparing 0.03059 mol  of Zn : 0.10 mol of HC with the stochiometry, we can deduce that HCl is by far greater. Hence the correct option is option 1.

Answer:

C

Explanation:

When an apple is cut (or bruised), oxygen is introduced into the injured plant tissue. When oxygen is present in cells, polyphenol oxidase (PPO) enzymes in the chloroplasts rapidly oxidize phenolic compounds naturally present in the apple tissues to o-quinones, colorless precursors to brown-colored secondary products

Answer:

Significant figures (also called significant digits) are an important part of scientific and mathematical calculations, and deals with the accuracy and precision of numbers. It is important to estimate uncertainty in the final result, and this is where significant figures become very important.

Explanation:

Answer:

1.67 × 10⁻⁷ mol H₂O

3.14 × 10¹³ atoms deuterium

Explanation:

How many moles of water were injected?

We have 3.00 μg of gaseous H₂O. To calculate the number of moles of water we will use the following relationships:

[tex]3.00 \mu g \times \frac{1g}{10^{6}\mu g } \times \frac{1mol}{18.02g} = 1.67 \times 10^{-7} mol[/tex]

If the sample contains 0.0156% deuterium, how many deuterium atoms were injected?

We will use the following relationships:

1 mole of water contains 6.02 × 10²³ molecules of water.

There are 2 hydrogen atoms per water molecule.

0.0156% of hydrogen atoms are deuterium atoms.

[tex]1.67 \times 10^{-7} molH_2O \times \frac{6.02 \times 10^{23}moleculesH_2O }{1molH_2O} \times \frac{2atomsH}{1moleculeH_2O} \times 0.0156 \% = 3.14 \times 10^{13} atomsD[/tex]

Answer:

Option A. 327 °C

Explanation:

The following data were obtained from the question:

Initial pressure (P1) = 12 atm

Initial temperature (T1) = 27 °C

Final pressure (P2) = 24 atm

Final temperature (T2) =?

Next, we shall convert 27 °C to Kelvin temperature. This can be obtained as follow:

Temperature (K) = Temperature (°C) + 273

Initial temperature (T1) = 27 °C

Initial temperature (T1) = 27 °C + 273

Initial temperature (T1) = 300 K

Next, we shall the temperature at which the cylinder will explode as follow:

Initial pressure (P1) = 12 atm

Initial temperature (T1) = 300 K

Final pressure (P2) = 24 atm

Final temperature (T2) =?

P1/T1 = P2/T2

12/300 = 24/T2

Cross multiply

12 × T2 = 300 × 24

Divide both side by 12

T2 = (300 × 24) /12

T2 = 600 K

Finally, we shall convert 600 K to celsius temperature.

This can be obtained as follow:

Temperature (°C) = Temperature (K) – 273

Temperature (K) = 600 K

Temperature (°C) = 600 – 273

Temperature (°C) = 327 °C

Therefore, the minimum temperature at which the cylinder will explode is

327 °C.

Answer:

b. 0.407

Explanation:

Acetic acid / Acetate ion is a buffer (Mixture of a weak acid, acetic acid, with its conjugate base, acetate ion) with pKa = -log Ka = 4.74.

The simplest way to determine the pH of a buffer is using Henderson-Hasselbalch formula:

pH = pKa + log [Conjugate base] / [Weak acid]

For acetic buffer with pH = 4.35:

4.35 = 4.74 + log [A⁻] / [HA]

-0.39 = log [A⁻] / [HA]

0.407 = [A⁻] / [HA]

Thus, right option is: