A buffer solution contains 0.472 M hydrocyanic acid and 0.342 M sodium cyanide. If 0.0194 moles of sodium hydroxide are added to 150 mL of this buffer, what is the pH of the resulting solution

Answers

Answer 1

Answer:

pH = 9.54.

Explanation:

Hello there!

In this case, since this is an acidic buffer due to the hydrocyanic acid, it will be firstly necessary for us to calculate the moles of both acid and conjugate base in 150 mL given their concentrations:

[tex]n_{acid}=0.472mol/L*0.150L=0.0708mol\\\\n_{base}=0.342mol/L*0.150L=0.0513mol[/tex]

Next, since the effect of adding NaOH, consume the acid and produce more base, we subtract 0.0194 moles from 0.0708 mol and add 0.0194 to 0.0513 mol for us to calculate the new moles:

[tex]n_{acid}^{new}=0.0708mol-0.0194mol=0.0514mol\\\\n_{base}^{new}=0.0513mol+0.0194mol=0.0707mol[/tex]

Thus, since the pKa of hydrocyanic acid is 9.40, we therefore use the Henderson-Hasselbach equation to calculate the pH of the resulting solution for the same volume:

[tex]pH=9.40+log(\frac{0.0707mol}{0.0514mol} )\\\\pH=9.54[/tex]

Which increase make sense since we added some strong base.

Regards!


Related Questions

A 14.570 g sample of CaCl2 was added to 12.285 g of K2CO3 and mixed in water. A 3.494 g yield of CaCO3 was obtained.
What is the limiting reagent?
-CaCO3
-K2CO3
-CaCl2

Calculate the percent yield of CaCO3.
yield of CaCO3= %

Answers

Answer:

Limiting reagent is the potassium carbonate.

Percent yield of calcium carbonate is: 39.3 %

Explanation:

The reaction is:

CaCl₂ + K₂CO₃ → CaCO₃ + 2KCl

Formula for percent yield is:

(Produced yield / Thoeretical yield) . 100

Firstly we determine the moles of each reactant, in order to say what is the limiting reagent: ratio is 1:1.

1 mol of chloride need 1 mol of carbonate.

14.570 g . 1 mol /110.98 g = 0.131 moles of CaCl₂

12.285 g . 1 mol / 138.2g = 0.0889 moles of carbonate.

Limiting reagent is carbonate. For 0.131 moles of CaCl₂ we need the same amount of carbonate and we have less moles.

Ratio is also 1:1, with calcium carbonate.

1 mol of potassium carbonate produces 1 mol of calcium carbonate

then, 0.0889 moles will produce the same amount of CaCO₃

We convert moles to mass: 0.0889 mol . 100.08g /mol = 8.89 g

That's the theoretical yield; to find the percent yield:

(3.494 g / 8.89g) . 100 = 39.3%

 

How many grams of KNO3 can dissolve in 100g of water at 20°C?

Answers

Answer:

30 grams of KNO3 can be dissolved.

Explanation:

Hello there!

In this case, since the solubility is defined as the maximum amount of solute that can be dissolved in a certain amount of solvent, usually 100 grams of water as function of the temperature, we will need to recall the graph for the solubility of KNO3 as shown on the attached file.

Thus, by identifying the curve for KNO3, we realize that at a temperature of 20 °C, the solubility is about 30 grams; which means 30 grams can be dissolved in 100 grams of water at 20 °C.

Regards!

Which is a property of barium (Ba)?
O A. It rarely reacts with other elements.
O B. It is brittle as a solid.
O c. It is very reactive.
O D. It does not conduct electricity.
Plzzzzz helppppp!!!

Answers

Answer:

a it rarely reach with other elements

why is platinum metal preferred to other metals for the flame test​

Answers

Answer:

Platinum is especially good for this because it is unreactive, and does not produce a color in the flame which will mask the presence of other metals.

Hope this answer is right!

Answer:

Hey mate, here is your answer

1. Platinum doesn't impart any color to the flame.

2. It is not oxidised under the high temperature of the flame from a bunsen burner.

3. It is almost chemically inert. Even at high temperatures, it remains unattacked by free radicals / acid radicals.

Therefore, platinum wire is crucial for a flame test. Also, a platinum wire should be thoroughly cleaned before using it for a new flame test.

A platinum wire is cleaned by dipping it into concentrated HNO3 and then placing it in the non luminous part of the bunsen flame. Otherwise, the perviously tested radicals will impart color to the flame, which may cause confusion.

Explanation:

Hope it helps you

1. How many atoms of chlorine are present in 1.70x1023 molecules Cl2?​

Answers

Explanation:

the answer is in the image above

A solution of KMnO4 has an absorbance of 0.539 when measured in the colorimeter. Determine the concentration of the KMnO4 given the following data for a calibration plot.

Concentration of KMNO4 (M) Absorbance
0.0150 0.081
0.0300 0.159
0.0450 0.260
0.0600 0.334

Answers

Answer:

Concentration of unknown solution is 0.0416 M

Explanation:

As we know  

Absorbance is equal to the product of molar absorptivity of KMnO4 m, path length and concentration

From the given set of graphical data, it is clear that the absorbance vs concentration is a straight line.  

From the graph, we can obtain-  

Y = 5.73 X – 0.0065

Absorbance = 0.232

0.232 = 5.73 X – 0.0065

X = 0.0416  

Concentration of unknown solution is 0.0416 M

How do we fix climate change?
The biggest problem of course is conspiracy theorys. Some say it is just a hoxe when really their chidrin or grandchidrin will sufer greatly from it. How do we educate ourselfs better?

Answers

Answer:

Hi so your answer is that to helping fix the climate change you have to : speak up , power your home with renewable engery , reduce water waste , dont waste food , and finally invest energy .

Explanation:

Really hope i helped , have a nice day :)

Answer:

we can reduce air pollution,which is one of the main cause of climate change.Climate change is not a hoxe if it is not attending the upcoming generations will suffer greatly.

A 8.29g sample of calcium sulfide was decomposed into its constituent elements, producing 4.61g of calcium and 3.68g of sulfur. Which of the statements are consistent with the law of constant composition (definite proportions)?

a. Every sample of calcium sulfide will have 44.4% mass of calcium.
b. Every sample of calcium sulfide will have 2.86 g of calcium.
c. The mass ratio of Ca to S in every sample of calcium sulfide is 1.25.
d. The ratio of calcium to sulfur will vary based on how the sample was prepared.
e. The mass percentage of calcium plus the mass percentage of sulfur in every sample of calcium sulfide equals 100%.

Answers

Answer:

d,e

Explanation:

A student named a particular compound 2-ethyl-3-methyl-2-butene. Assuming that the student's choice actually corresponded to the correct distribution of the double bond and the substituents, what is the correct IUPAC name for this compound

Answers

Answer:

2-ethyl-3-methylbut-2-ene

Explanation:

The whole idea of IUPAC nomenclature is to devise a universally accepted system of writing the name of a compound from its structure.

According to IUPAC nomenclature, the root of the compound is the longest carbon chain. The substituents are named in alphabetical order and in such a way as to give each one the lowest number. The position of the functional group is indicated accordingly.

For the compound in question, its correct IUPAC name is 2-ethyl-3-methylbut-2-ene.

atomic number of element is 15 write a formula of an oxide​

Answers

Answer:

Atomic Number. 15=phosphorus

Valency=3

So, Oxide=P203

Calculate [H3O+] and [OH−] for each of the following solutions at 25 ∘C given the pH.
pH= 2.89

Answers

Answer: The value of [tex][H_{3}O^{+}][/tex] is 0.0012 M and [tex][OH^{-}][/tex] is [tex]1.02 \times 10^{-14}[/tex].

Explanation:

pH is the negative logarithm of concentration of hydrogen ion.

It is given that pH is 2.89. So, the value of concentration of hydrogen ions is calculated as follows.

[tex]pH = - log [H^{+}]\\2.89 = - log [H^{+}]\\conc. H^{+} = 0.0012 M[/tex]

The relation between pH and pOH value is as follows.

pH + pOH = 14

0.0012 + pOH = 14

pOH = 14 - 0.0012 = 13.99

Now, pOH is the negative logarithm of concentration of hydroxide ions.

Hence, [tex][OH^{-}][/tex] is calculated as follows.

[tex]pOH = - log [OH^{-}]\\13.99 = - log [OH^{-}]\\conc. OH^{-} = 1.02 \times 10^{-14} M[/tex]

Thus, we can conclude that the value of [tex][H_{3}O^{+}][/tex] is 0.0012 M and [tex][OH^{-}][/tex] is [tex]1.02 \times 10^{-14}[/tex].

pasagot po please!!

science po ito pasagot po matino need ko po!!​

Answers

Explanation:

Efficiency = (output/input)×100%

70% = output/(800 W)

which means

output = 0.70×(800 W) = 560 W

What is the concentration of s solution that contains 55 mL of alcohol per 145 mL solution?​

Answers

Answer:

37.9% v/v

Explanation:

Since both the alcohol and solution are presumed to be liquid, this concentration can be expressed as a volume concentration (or % v/v):

volume concentration = volume of solute / volume of solution

[tex]\% v/v = 55/145= 0.379[/tex]

The seagulls on the beach -​

Answers

Seagulls like beaches because they can find food

Liquid hexane
(CH,(CH), CH) will react with gaseous oxygen (0) to produce gaseous carbon dioxide (CO2) and gaseous water (1,0). Suppose 1.72 g
of hexane is mixed with 8.0 g of oxygen. Calculate the maximum mass of water that could be produced by the chemical reaction. Be sure your answer has the
correct number of significant digits.

Answers

Answer: The mass of [tex]H_2O[/tex] produced is 2.52 g

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass.  The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

For hexane:

Given mass of hexane = 1.72 g

Molar mass of hexane = 86.18 g/mol

Putting values in equation 1, we get:

[tex]\text{Moles of hexane}=\frac{1.72g}{86.18g/mol}=0.020mol[/tex]

For oxygen gas:

Given mass of oxygen gas = 8.0 g

Molar mass of oxygen gas= 32 g/mol

Putting values in equation 1, we get:

[tex]\text{Moles of water}=\frac{8.0g}{32g/mol}=0.25mol[/tex]

The chemical equation for the combustion of hexane follows:

[tex]2C_6H_{14}+19O_2\rightarrow 12CO_2+14H_2O[/tex]

By stoichiometry of the reaction:

If 2 moles of hexane reacts with 19 moles of oxygen gas

So, 0.020 moles of hexane will react with = [tex]\frac{19}{2}\times 0.020=0.19mol[/tex] of oxygen gas

As the given amount of oxygen gas is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.

Thus, hexane is considered a limiting reagent because it limits the formation of the product.

By the stoichiometry of the reaction:

If 2 moles of hexane produces 14 moles of [tex]H_2O[/tex]

So, 0.020 moles of hexane will produce = [tex]\frac{14}{2}\times 0.020=0.14mol[/tex] of [tex]H_2O[/tex]

We know, molar mass of [tex]H_2O[/tex] = 18 g/mol

Putting values in above equation, we get:

[tex]\text{Mass of }H_2O=(0.14mol\times 18g/mol)=2.52g[/tex]

Hence, the mass of [tex]H_2O[/tex] produced is 2.52 g

carbon dioxide gas evolve during the fermentation of sugar which was collected at 22.5°C and 0.945 ATM after perfect strangers in the volume was found to be 25.0 ML how many grams of carbon dioxide were collected

Answers

Answer:

0.043 grams

Explanation:

We can find the mass of carbon dioxide as follows:

[tex] m = n*M [/tex]

Where:

n: is the number of moles

M: is the molar mass = 44.01 g/mol

First, we need to calculate the number of moles. We can use the Ideal gas equation:

[tex] PV = nRT [/tex]

Where:

P: is the pressure = 0.945 atm

V: is the volume = 25.0 mL  

R: is the gas constant = 0.082 L*atm/(K*mol)

T: is the tempearture = 22.5 °C

[tex]n = \frac{PV}{RT} = \frac{0.945 atm*25 mL*\frac{1 L}{1000 mL}}{0.082 L*atm/K*mol*(22.5 + 273) K} = 9.75 \cdot 10^{-4} moles[/tex]

Hence, the mass is:

[tex]m = 9.75 \cdot 10^{-4} moles*44.01 g/mol = 0.043 g[/tex]

Therefore, 0.043 grams were collected.

                         

I hope it helps you!

Plz help!!!! NO LINKS

Answers

Answer:

481.16 cm³

Explanation:

From the question given above, the following data were obtained:

Height (h) = 11.72 cm

Diameter (d) = 7.23 cm

Pi (π) = 3.14159

Volume of cylinder (V) =?

Next, we shall determine the radius. This can be obtained as follow:

Diameter (d) = 7.23 cm

Radius (r) =?

r = d/2

r = 7.23 / 2

r = 3.615 cm

Finally, we shall determine the volume of the cylinder. This can be obtained as shown below:

Height (h) = 11.72 cm

Pi (π) = 3.14159

Radius (r) = 3.615 cm

Volume of cylinder (V) =?

V = πr²h

V = 3.14159 × 3.615² × 11.72

V = 3.14159 × 13.068225 × 11.72

V = 481.16 cm³

Therefore, the volume of the cylinder is 481.16 cm³.

For the iron thiocyanate system, what is the value of the equilibrium constant, Kc, if the following are the concentrations of all species present. Provide your answer to three digits after the decimal.

FeSCN2+ 0.501
Fe3+ 0.494
SCN- 0.639

Answers

Answer:

Kc = 0.630

Explanation:

The equilibrium of the thiocyanate system occurs as follows:

FeSCN²⁺(aq) ⇄ Fe³⁺(aq) + SCN⁻(aq)

And equilibrium constant, kc, is:

Kc = [SCN⁻] [Fe³⁺] / [FeSCN²⁺]

Replacing with the gven concentrations:

Kc = 0.639M*0.494M / 0.501M

Kc = 0.630

The product of an organic reaction is analyzed by column chromatography using silica as the stationary phase and toluene as the mobile phase.

a. True
b. False

Answers

Answer:

The product of an organic reaction is analyzed by column chromatography using silica as the stationary phase and toluene as the mobile phase.

Explanation:

The given statement is true.

In chromatography silica gel is used as the predominant stationary phase.

Since silica gel is a good adsorbent.

It is a polar adsorbent.

In order to remove polar components, silica gel is used as the stationary phase.

Answer is a.true.

Electron sharing can be depicted by a Lewis dot structure, in which element symbols are surrounded by dots that represent the valence electrons (electrons in the ___________ shell). A ______________ bond is the sharing of a pair of valence electrons by _____________ atoms. Hydrogen has _____________ valence electron(s) in the first shell, but the capacity of the shell is ______________ electron(s). When a hydrogen atom comes close enough to a carbon atom for their orbitals to overlap, they can share their electrons. The hydrogen atom is now associated with _______________ electron(s) and a ______________ bond is formed. As a result, one of the structures does not make sense because hydrogen has only ____________ valence electron(s) to share, so it cannot form bonds with two atoms.

Answers

Answer:

Outermost

Covalent

Two

One

Two

Two

Covalent

One

Explanation:

A covalent bond is formed when an atom shares two electrons with another atom. These shared electrons could be contributed by each of the bonding atoms or by only one of the bonding atoms.

Hydrogen has the electronic configuration of 1s1. This implies that it has only one electron in its valence shell although the 1s shell can accommodate two electrons. When the atomic orbitals of carbon and hydrogen overlap, they share two electrons and hydrogen is now associated with two electrons in a covalent bond.

Since hydrogen possesses only one valence electron, it can not be bonded to two atoms.

The carbon-carbon bonds in benzene are:
O a) Easily broken in chemical reactions
b) A hybrid between double bonds and single bonds
c)
Identical to the carbon-carbon bonds in cyclohexene
d) Identical to the carbon-carbon bonds in cyclohexane
please hurry

Answers

Answer:

a

Explanation:

Easily broken in chemical reactions

In an oxidation-reduction reaction, the substance oxidized always ________. a. takes on oxygen atoms b. gives up hydrogen atoms c. gains electrons d. loses electrons e. becomes a charged species

Answers

Answer:

Explanation:

Let us define oxidation and reduction.

Oxidation and reduction deal with the transferring of electrons between reactants. The reactant that loses electrons is oxidized, while the reactant that gains electrons is reduced.

In an oxidation-reduction reaction, the substance oxidized always loses electrons and the correct option is option D.

An oxidation-reduction (redox) reaction is a type of chemical reaction that involves the transfer of electrons between species. It consists of two half-reactions: an oxidation half-reaction, where a species loses electrons and increases its oxidation state, and a reduction half-reaction, where a species gains electrons and decreases its oxidation state.

In an oxidation half-reaction, the species that is oxidized is called the reducing agent or the electron donor, as it donates electrons. In a reduction half-reaction, the species that is reduced is called the oxidizing agent or the electron acceptor, as it accepts electrons.

Thus, the ideal selection is option D.

Learn more about Oxidation-reduction reactions, here:

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Lab 2: paper chromatography of organic dyes
Picture of questions below.

Answers

Answer:

The three primary colors used when mixing dyes or paints are red, yellow, and blue. Other colors are often a mixture of these three colors. Try running a chromatography test again with non-primary-color markers, like purple, brown, and orange.

Explanation:

Mixtures that are suitable for separation by chromatography include inks, dyes and colouring agents in food. ... As the solvent soaks up the paper, it carries the mixtures with it. Different components of the mixture will move at different rates. This separates the mixture out.

What is the quantity of
heat required to raise the
temperature of 500 g of
iron by 2°C?
The specific heat capacity
of iron is 500 J/(kg °C)

Answers

Answer:

The quantity of  heat required to raise the  temperature of 500 g of  iron by 2°C is 500 J.

Explanation:

Calorimetry is responsible for measuring the amount of heat generated or lost in certain physical or chemical processes.

The sensible heat of a body is the amount of heat received or transferred by a body when undergoing a temperature variation (Δt) without there being a change in physical state (solid, liquid or gaseous).

Its mathematical expression is the fundamental equation of calorimetry. This is:

Q = c * m * ΔT

where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

In this  case:

Q= ?c= 500 [tex]\frac{J}{kg*C}[/tex]m= 500 g= 0.500 kgΔT= 2 C

Replacing:

Q= 500 [tex]\frac{J}{kg*C}[/tex] *0.500 kg*2 C

Solving:

Q= 500 J

The quantity of  heat required to raise the  temperature of 500 g of  iron by 2°C is 500 J.

Molybdenum (Mo) crystallizes with a body-centered cubic lattice and has an atomic radius of 136.1 pm.

a. Calculate the density of molybdenum in g/cm^3. Show all work. Include units with all numbers and show how units cancel.
b. Calculate the density of molybdenum in g/cm^3

Answers

it’s x200 plus 300 that’s why it is that answer

What is represented by the chemical formula
PbCl2(s)?
A) a substance
B) a solution
C) a homogeneous mixture
D) a heterogeneous mixture

Answers

Answer:

what is represented is a substance

PbCl2(s) is a substance

When writing chemical formulae or equations , we use chemical symbols to express the state of matter and  the conditions  of an element,  compound or  reactants .

The symbols to represent physical states of matter are are

(s)  This tells that the substance is in  solid state

(aq )  means aqueous,  It tells that the substance has been dissolved and it is in a solution.

(l)This tells that the substance is in liquid state

(g)This tells that the substance is in gaseos state

Now, PbCl2(s) is a substance in the solid state.

See here:https://brainly.com/question/2167551

13. The attraction between water molecules and an Na+
ion or a Cl- ion occurs because water molecules are
A) linear
B) symmetrical
C) polar
D) nonpolar

Answers

Answer:

C) Polar

Explanation:

The correct answer is polar

The attraction of sodium and chloride ions by the water is mediated by the polar nature of water. Thus, option C is correct.

What is polarity?

The polarity is given as the formation of the partial positive and negative charge over the species in the ionization process.

Water molecule is having one hydrogen bounded with 2 oxygen atoms, and oxygen being more electronegative develops a partial negative charge, while hydrogen develops a partial positive charge.

The positive charge hydrogen and the negative charge oxygen attracts the opposite charge sodium and chloride ions. Thus, the attraction is mediated due to the polar nature of water. Hence, option C is correct.

Learn more about polarity, here:

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phương pháp VI PHÂN ĐỒ THỊ để xác định bậc phản ứng

Answers

Answer:

mwlooy kagabi jal

64 JAHA VI PHÂN KAY


The formula for europium oxide is Eu203. On the basis of this information, the formula for the chlorate of europium would be expected to be

Answers

Answer:

Eu(ClO3)3

Explanation:

The chlorate ion is written as follows, ClO⁻ ₃. We can see from this that the ion is univalent.

From the formula, Eu203, it is easy to see that the europium ion is trivalent.

Hence, when a compound is formed between the europium ion and chlorate ion, the compound will be written as Eu(ClO3)3.

This is so because, when ionic compounds are formed, there is an exchange of valence between the ions in the compound. This gives the final formula of the ionic substance.

which is a characteristic of oxygen​

Answers

Answer:

Characteristics of oxygen are as follows:

In normal conditions oxygen is a colourless, odourless and insipid gas.It condensates in a light blue liquid.Oxygen is part of a small group of gasses literally paramagnetic and it's the most paramagnetic of all.Liquid oxygen is also slightly paramagnetic.
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