Plz help me plz I am timed!!

Answer: 49.8 g

Explanation: molar mass M(KI) = 39.1+ 126.9 = 166 g/mol

Mass m= n·M= 0.3 mol· 166 g/mol

Answer:

4.2 g

Explanation:

Answer:

CH3COOH - CH3COONa since its pKa is closest to the required pH.

Explanation:

Hello there!

In this case, in agreement with the theory of buffers as solutions able to withstand severe pH changes due to the addition of acidic or basic substances, it is possible to set up a generation equilibrium expression for the acids herein given:

[tex]Ka=\frac{[A^-][H_3O^+]}{[HA]}[/tex]

Which leads to the Henderson-Hasselbach equation:

[tex]pH=pKa+log(\frac{[A^-]}{[HA]} )[/tex]

Thus, since all the buffers have [A-]=[HA]=0.10M, the log part becomes 0 and therefore the best buffer will have the closest pKa to the required pH, which is CH3COOH - CH3COONa since its pKa is 4.74.

Best regards!

[tex]CH_3COOH\; and\; CH_3COONa[/tex] can be used to prepare a pH buffer, if 0.10 M solution available of the solutions.

Buffer is a solution, that resist change in pH, by adding or removing H+ ions to the solution.

Maintaining a constant pH is necessary to complete many reactions.

In blood, bicarbonates maintain the pH of the body.

[tex]CH_3COOH\; and\; CH_3COONa[/tex] have approx the nearest pH, so they can be used to make a buffer.

Thus, the correct options are [tex]CH_3COOH\; and\; CH_3COONa[/tex]

Learn more about buffer

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Answer:

7. Option D

Explanation:

Solubility increases with the increase in temperature of the solution. It is so because the increase in temperature leads to increase in kinetic energy which then breaks the solute particles held together by intermolecular attractions.

Hence, option D is correct

Answer:

Fires --> These consume fuel and convert chemical energy stored in that fuel into thermal light and sound energy.

Decay -->The breakdown of dead plants and animals releases thermal energy.

Earth --> Thermal energy comes from deep inside and it is called geothermal energy.

The correct answer is solution B!

Answer:

[tex]1s^2\, 2s^2[/tex].

Explanation:

Electron orbitals in an atom (e.g., [tex]1s[/tex]) are denoted with:

There are two aspects to consider when finding the electron configuration of an atom:

The [tex]s[/tex] orbital in each shell could hold up to [tex]2 \times 1 = 2[/tex] electrons (one [tex]s\![/tex] orbital per shell, with up to two electrons.)

The [tex]p[/tex] orbitals in each shell could hold up to [tex]2 \times 3 = 6[/tex] electrons (three [tex]p\![/tex] orbitals per shell, with up to two electrons in each orbital.)

The [tex]d[/tex] orbitals in each main shell could hold up to [tex]2 \times 5 = 10[/tex] electrons (five [tex]d\![/tex] orbitals per shell, with up to two electrons in each orbital.)

Refer to the order in which the orbitals are filled (Aufbau principle.)

All four electrons of Beryllium are thus assigned to the [tex]1s[/tex] and [tex]2s[/tex] orbitals. In a ground-state Beryllium atom, orbitals [tex]2p[/tex] and beyond would contain no electrons.

Notation:

Write the non-empty orbitals in the order by which they are filled:

[tex]1s^2\, 2s^2[/tex].

Answer:

Answer: pH = 2.72

Explanation:

Calculate the pH of 0.010 M HNO2 solution. The K, for HNO2 is 4.6 x 104 

Answer:

it's dairy

Explanation

Answer:

Given : Diatomic molecule at 273K

'q' absorbed = positive = +100Cal = 100 x 4.184J = 418.4J

'W' done by system = negative = -209J

By first law of thermodynamics;

ΔU = q + W = 418.4 + (-209) = 209.4J

We know for diatomic molecule Cv=25R and CvΔT=ΔU

CvΔT=209.4

 25RΔT=209.4

ΔT=5R209.4×2

And, Heat exchange=Cm×ΔT 

where; Cm is molar heat capacity

Cm=ΔTHeat Exchange

substituting values for Heat Exchange = 418.4 and ΔT=5R209.4×2

Cm=5R

Answer:

Is there any other part to this question? If not I'm pretty sure the answer is 205.5 kJ

Explanation:

Answer:

822 kJ; 411 kJ/mol.

Explanation:

A chemist measures the enthalpy change during the following reaction: ()()()Use this information to complete the table below. Round each of your answers to the nearest kJ/mol. 1. ()()()Solution:  given reaction is 2Na + Cl2 --> 2NaCl         delta H = -822 KJ 1) 1/2Na + 1/4Cl2 --> 1/2NaCl divide the coficiant of given.

Answer:

[tex]V_2=1228.9L[/tex]

Explanation:

Hello there!

In this case, given the pressure, temperature and volume of the gas, we notice that we need the combined ideal gas as shown below:

[tex]\frac{P_2V_2}{T_2} =\frac{P_1V_1}{T_1}[/tex]

Thus, solving for the final volume, V2,  we would obtain:

[tex]V_2=\frac{P_1V_1T_2}{T_1P_2}[/tex]

Now, we plug in the data and make sure the temperature must be in Kelvins to obtain:

[tex]V_2=\frac{200atm*6.0L*(25+273)K}{(18+273.15)K(1.0atm)}\\\\V_2=1228.9L[/tex]

Best regards!

Answer: Animals found in the Arctic tundra include herbivorous mammals (lemmings, voles, caribou, arctic hares, and squirrels), carnivorous mammals (arctic foxes, wolves, and polar bears), fish (cod, flatfish, salmon, and trout), insects (mosquitoes, flies, moths, grasshoppers, and blackflies), and birds (ravens, snow buntings

The lives in Artic tundra biome is caribou.

Artic tundra biome is the northernmost biome, which covers the land of the arctics with the ice caps.

Climate of this Artic tundra biome is almost cold means the temperature in winter season of this region is about -34 degree celsius. In this region small animals like Norway lemmings as well as large animals like caribou are present which have high amount of fat to rescue from the cold.

Hence, option (a) is correct.

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Answer:

Explanation:

c it’s see it

Answer:

Mass (kg) × Acceleration (m/s²) = Force (N)

Answer:

what grade is this?

the answer is gold cause oil wood and glass are electrical insulators

Answer:

See explanation

Explanation:

a) The magnitude of intermolecular forces in compounds affects the boiling points of the compound. Neon has London dispersion forces as the only intermolecular forces operating in the substance while HF has dipole dipole interaction and strong hydrogen bonds operating in the molecule hence HF exhibits a much higher boiling point than Ne though they have similar molecular masses.

b) The boiling points of the halogen halides are much higher than that of the noble gases because the halogen halides have much higher molecular masses and stronger intermolecular forces between molecules compared to the noble gases.

Also, the change in boiling point of the hydrogen halides is much more marked(decreases rapidly)  due to decrease in the magnitude of hydrogen bonding from HF to HI. The boiling point of the noble gases increases rapidly down the group as the molecular mass of the gases increases.

Answer:

A via A P E X

The entity that would make ΔG to become negative at a given enthalpy and entropy is Changing the temperature (Option A)

ΔG = ΔH – TΔS

Where

NOTE

ΔG = +ve (non spontaneous)

ΔG = 0 (equilibrium)

ΔG = –ve (spontaneous)

From the Gibbs free energy equation, we can see that the entities that makes us the equation are

Thus, we can conclude that the correct answer to the question is: changing the temperature (Option A) since the equation has nothing to do with neither concentration, pressure nor volume

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Answer:

[tex]0.769\ \text{M}[/tex]

Explanation:

Mass of stock solution = 20 g

Molar mass of NaOH = 40 g/mol

Volume of stock solution = 0.150 mL

[tex]M_2[/tex] = Concentration of NaOH for the final solution

[tex]V_1[/tex] = Amount of stock solution taken = 15 mL

[tex]V_2[/tex] = Total volume of solution = 65 mL

Molarity is given by

[tex]M_1=\dfrac{\text{Mass}}{\text{Molar mass}\times \text{Volume}}\\\Rightarrow M_1=\dfrac{20}{40\times 0.15}\\\Rightarrow M_1=\dfrac{10}{3}[/tex]

We have the relation

[tex]M_1V_1=M_2V_2\\\Rightarrow M_2=\dfrac{M_1V_1}{V_2}\\\Rightarrow M_2=\dfrac{\dfrac{10}{3}\times 15}{65}\\\Rightarrow M_2=0.769\ \text{M}[/tex]

The concentration of NaOH for the final solution is [tex]0.769\ \text{M}[/tex].

Answer:

Explanation:

It is 11

Answer:

I honestly don't know but I hope you get more points! ;D

Explanation:

Answer:

A) Wood burning

system : Wood.

surroundings : atmosphere

Enthalpy : Exothermic

B) Water Freezing system

System : Refrigerator

surroundings :  water in the refrigerator

enthalpy change : Endothermic

C) Sweat evaporating

System :  Human being

surroundings : Air nearby

Enthalpy change : exothermic

D) Chemical Hand-warmer

system : Hand warmer pack

Surroundings : human palms

Enthalpy Change : Exothermic

Explanation:

A) Wood burning

system : Wood

surroundings : atmosphere

Enthalpy : Exothermic

This system give away energy to its surroundings hence its enthalpy change is exothermic

B) Water Freezing system

System : Refrigerator

surroundings :  water in the refrigerator

enthalpy change : Endothermic

The system absorbs heat from what is put inside(surroundings ) of it hence this is na endothermic system

C) Sweat evaporating

System :  Human being

surroundings : Air nearby

Enthalpy change : exothermic

This is an exothermic reaction ( enthalpy change ) because the system gives out heat to the surrounding

D) Chemical Hand-warmer

system : Hand warmer pack

Surroundings : human palms

Enthalpy Change : Exothermic

There is movement of heat from the system to the surrounding hence it is an exothermic reaction

Answer:

The optical properties of a material define how it interacts with light. The optical properties of matter are studied in optical physics, a subfield of optics. Wiki.pedia

Explanation:

Answer:

Reaction that takes place at the Zn electrode is oxidation:

Zn ⇄  Zn²⁺  +  2e⁻

Explanation:

This excersise explains the structure of a typical battery, that is useful to study electrochemistry.

AgNO₃ → Ag⁺ + NO₃

ZnSO₄ → Zn²⁺  +  SO₄⁻²

Generally batteries contains 2 electrodes, where we have 2 conductive metallic. Batteries work to obtain electricity from a chemistry reaction which is always a redox type. One electrode releases electrons while the other catch them. Electrons travel from the anode to cathode, so in the anode, the e⁻ are released.

Reaction that takes place at the Zn electrode is oxidation:

Zn ⇄  Zn²⁺  +  2e⁻

Oxidation state is increased, electrons are free to go to cathode, where the other element decreases the oxidation state:

Ag⁺ + e⁻  ⇄ Ag

In the middle of the battery, the salt bridge (generally KCl) contributes the redox with more charges. Cl⁻ for the anode and K⁺ for the cathode.

Note that the same amount of electrons travel from anode to cathode, because in this example, Ag gained 1 mol and Zn released 2 moles.

The scheme for the battery is:

⁻  Zn(s) / Zn²⁺ (aq) //  Ag⁺ (aq) / Ag (s) ⁺

         1 M                               1 M                      

Where the first place represents the anode, // represents the salt bridge and then, the cathode.  Below, we write the molar concentration of each salt.

Answer:

A) atomic size

Explanation: