Please help

15 points

Answer:

0.847 molecule.

Explanation:

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

Mass of X₄Z₃ = 3.93×10¯²² g

Number of molecules of X₄Z₃ =?

Avogadro's number = 6.022×10²³ molecules

Next, we shall determine the molar mass of X₄Z₃. This can be obtained as follow:

Molar mass of X₄Z₃ = (4×59.45) + (3×13.84)

= 237.8 + 41.52

= 279.32 g/mol

Finally, we shall determine the number of molecules in 3.93×10¯²² g of X₄Z₃. This can be obtained as follow:

From Avogadro's hypothesis,

1 mole of X₄Z₃ = 6.022×10²³ molecules

But 1 mole of X₄Z₃ = 279.32 g

Thus we can say that:

279.32 g = 6.022×10²³ molecules

Therefore,

3.93×10¯²² g = 3.93×10¯²² × 6.022×10²³ / 279.32

3.93×10¯²² g = 0.847 molecule.

Thus, 3.93×10¯²² g of X₄Z₃ contains 0.847 molecule.

Answer:

The system releases energy to the environment, because its internal energy decreases.

The entropy of the surroundings increases (AS surr > 0) because the surroundings absorb heat released by the reaction, and become more disordered.

The entropy of the system decreases (AS sys < 0) because the closure of the ring reduces the number of conformations the ring can adopt.

The enthalpy or internal energy of the system decreases (AH sys < 0) because the electrons that form the bond enter an orbital that is at a lower energy.

Explanation:

Now we know that when a reaction is exothermic heat is given off. In this case, we have a reaction that connects the ends of a chain of carbons to form a ring.  The bonding electrons now move into a lower energy bonding sigma molecular orbital.

This leads to a decrease in the entropy and enthalpy of the system because energy is given off, the closure of the ring reduces the number of conformations the ring can adopt and  the electrons that form the bond enter an orbital that is at a lower energy.

The entropy of the surroundings is increased as energy is given out. The surroundings absorb heat released by the reaction, and become more disordered.

Answer:

True

Explanation:

Sound waves traveling through air are indeed longitudinal waves with compressions and rarefactions. As sound passes through air (or any fluid medium), the particles of air do not vibrate in a transverse manner.

Answer:

true

Explanation:

ape x

Answer:

[tex]M=1.05M[/tex]

Explanation:

Hello!

In this case, since the formula for the calculation of molarity is defined in terms of moles and volume in liters as shown below:

[tex]M=\frac{n}{V}[/tex]

Whereas the moles are computed by considering the molar mass of CaCO3 (100.09 g/mol):

[tex]n=47.4g*\frac{1mol}{100.09g}=0.4736mol[/tex]

Thus, we obtain:

[tex]M=\frac{0.4736mol}{0.450L}\\\\M=1.05M[/tex]

Best regards!

Answer:

13.22 L

Explanation:

Given data:

Volume of ammonia = ?

Mass of ammonia = 10.0 g

Temperature = standard = 273.15 K

Pressure = standard = standard = 1 atm

Solution:

First of all we will calculate the number of moles of ammonia.

Number of moles = mass/molar mass

Number of moles = 10.0 g/ 17 g/mol

Number of moles = 0.59 mol

one mole of any substance at standard temperature and pressure occupy 22.41 L . Thus, 0.59 moles of ammonia will occupy,

0.59 mol × 22.4 L / 1 mol

13.22 L

Answer: 12.4L

Explanation:

mw NH3 18

1 mole = 22.4L

10g = 10/18 moles

Answer:

You will remember that the difference between an aldehyde and a ketone is the presence of a hydrogen atom attached to the carbon-oxygen double bond in the aldehyde. Ketones don't have that hydrogen. ... Aldehydes are easily oxidized by all sorts of different oxidizing agents: ketones are not.

Answer:

Measure the volume of water poured into a graduated cylinder, then place the object in the water and remeasure the volume. The difference between the two volume measurements is the volume of the object. Now simply divide the mass by the volume to calculate the density of the object.

Answer: 0.800 M

Basically, the ratio is 2:1, so when you have 1 M of Li2HPO4 it means you have 2 M in the concentration of lithium ions. So knowing the ratio, we know we just need to multiply 0.400 x 2.

I'm bad at explaining it, but got it right on chem101 sooo

The concentration of lithium ion, Li⁺ in 0.4 M Li₂HPO₄ is 0.8 M.

The concentration of a substance is simply the amount of the substance in 1 L of water.

To obtain the concentration of lithium ion, Li⁺ in Li₂HPO₄, we'll begin by writing the dissociation equation of Li₂HPO₄. This is illustrated below:

From the balanced equation above,

1 mole of Li₂HPO₄ produced 2 moles of Li²⁺.

Finally, we shall determine the concentration of lithium ion, Li⁺ in 0.4 M Li₂HPO₄. This can be obtained as follow:

From the balanced equation above,

1 mole of Li₂HPO₄ produced 2 mole of Li⁺.

Therefore, 0.4 M Li₂HPO₄ will produce = 2 × 0.4 = 0.8M Li²⁺

Thus, 0.8 M lithium ion, Li⁺ is present in the solution.

Learn more: https://brainly.com/question/19536817

Answer:

2812.6 g of H₂SO₄

Explanation:

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

Mole of H₂SO₄ = 28.7 moles

Mass of H₂SO₄ =?

Next, we shall determine the molar mass of H₂SO₄. This can be obtained as follow:

Molar mass of H₂SO₄ = (1×2) + 32 + (16×4)

= 2 + 32 + 64

= 98 g/mol

Finally, we shall determine the mass of H₂SO₄. This can be obtained as follow:

Mole of H₂SO₄ = 28.7 moles

Molar mass of H₂SO₄ =

Mass of H₂SO₄ =?

Mole = mass / Molar mass

28.7 = Mass of H₂SO₄ / 98

Cross multiply

Mass of H₂SO₄ = 28.7 × 98

Mass of H₂SO₄ = 2812.6 g

Thus, 28.7 mole of H₂SO₄ is equivalent to 2812.6 g of H₂SO₄

Answer:

The outer shell of the new star will start to expand.

Explanation:

The new star will continue to glow for millions or even billions of years. As it glows, hydrogen is converted into helium in the core by nuclear fusion. The core starts to become unstable and it starts to contract. The outer shell of the star, which is still mostly hydrogen, starts to expand.

Explanation provided by:

StarChild: Stars - NASA

Answer:

I dunno,  what is the answer

Explanation:

Answer:

2.69 * 10^-6 Mol/L

Explanation:

The equation of the reaction is;

Cl2CHCO2CH3 -------------------> Cl2CHCO2H + CH3OH

To convert from ppm concentration to Mol/L, we have

M = ppm/MM * 1000

Where;

M = mol/l

MM= Molar mass

M = 1/142.97 g/mol * 1000 =

M= 6.99 * 10^-6 Mol/L

For first order reaction;

ln[A] = ln[A]o -kt

Given that

[A]o = 6.99 * 10^-6 Mol/L

[A]=??

k= 2.7 x 10-4/sec

t= 30 mins * 60 = 1800 s

ln[A] = ln[6.99 * 10^-6] -   (2.7 x 10-4 * 1800)

ln[A] = -11.87 - 0.486

ln[A] = -12.356

[A] = e^(-12.356)

[A] = 4.3 * 10^-6 Mol/L

Concentration of methanol present after 30 mins= 6.99 * 10^-6 - 4.3 * 10^-6 = 2.69 * 10^-6 Mol/L

Answer:

Boiling Water

Explanation:

Boiling water is an example of physical change and not and not a chemical change because the water vapor still has the same molecular structure as liquid water.If the bubbles were caused by the decomposition of a molecule into gas then boiling would be a chemical change.

Answer:

A chemical change results from a chemical reaction, while a physical change is when matter changes forms but not chemical identity. Examples of chemical changes are burning, cooking, rusting, and rotting. Examples of physical changes are boiling, melting, freezing, and shredding

Explanation:

Answer:

50g

Explanation:

At the end of the burning process, the mass of the jar and smoke should be 50g after the candle burning is done.

In most systems, the law of conservation of matter finds expression. According to this law "matter is neither created nor destroyed but atoms are rearranged".

In this kind of system, no matter is allowed to escaped and the starting mass of the reactants compared to that of the product will be the same.

[OH⁻]= 2.7 x 10⁻¹³

pH = 1.431

Given

[H3O+] = 3.7x10⁻² M.

Required

the [OH-] and pH

Solution

pH = - log [H⁺]

pH = 2 - log 3.7

pH = 1.431

pOH = 14 - 1.431

pOH = 12.569

pOH = - log [OH⁻]

[OH⁻]= 2.7 x 10⁻¹³

or

[OH-][H3O+]=10⁻¹⁴

[OH-]=10⁻¹⁴ : 3.7 x 10⁻²

[OH-] = 2.7 x 10⁻¹³

Answer:

C. H20(aq)

Explanation:

Answer:

Synthesis

Explanation:

Two reactants are becoming one product, so it is a synthesis reaction.

Decomposition is the opposite, so when one molecule becomes simpler atoms.

Example: 2NaCl -> Cl2 + Na

Combustion is reaction with a product of water and carbon dioxide.

Example: CH4 + 2O2 -> CO2 + 2H2O

Single displacement is when one atom takes the place of the other.

Example: K + NaCl -> KCl +Na (where K took the place of Na)

Double displacement is like single displacement but it happens twice. Think of it like the atoms exchanging partners.  

Example: HCl +NaH -> NaCl + HOH

Answer:

(i) N2(g)+3H2(g) -->2NH3(g) - When the equilibrium changes, the concentrations of all substances involved in the equilibrium must also change. For our equilibrium reaction: N2(g) + 3H2(g) ⇔ 2NH3(g) + Heat

(ii) 2 H2(g) + O2(g) --> 2 H2O(g) - Synthesis Reaction

HENCE BOTH THE REACTIONS COULD BE CLASSIFIED AS SYNTHEYIC REACTION

PLEASE DO MARK MY ANSWER AS THE BRAINLIEST..

<HOPE IT HELPS>

Answer:

[tex]8.876\times 10^{18}\ km^2[/tex]

Explanation:

In this problem, we need to convert [tex]8.876 \times 10^{12}\ m^2[/tex] to km².

We know that,

1 km = 1000 m

⇒ 1 km² = 10⁶ m²

So,

[tex]8.876 \times 10^{12}\ m^2=8.876 \times 10^{12}\times 10^6\ km^2\\\\=8.876\times 10^{18}\ km^2[/tex]

So, [tex]8.876 \times 10^{12}\ m^2[/tex] is equal to [tex]8.876\times 10^{18}\ km^2[/tex].

The given question is incomplete. The complete question is:

A reversible reaction is said to have reached equilibrium when which of the following conditions is established?

a. concentration of reactants and products are equal

b. opposing reactions cease

c. speeds of opposite reactions become equal

d. temperature of opposite reactions become equal

Answer: c. speeds of opposite reactions become equal

Explanation:

Equilibrium state is the state when reactants and products are present but the concentrations does not change with time.The state of equilibrium refers to the dynamic state as both forward and backwad reactions continue.

For a chemical equilibrium reaction, equilibrium state is achieved when the rate of forward reaction becomes equals to rate of the backward reaction.

Thus at chemical equilibrium, the amount of product and reactant remains constant because the rates of the forward and reverse reactions are equal.

because im  d and god is go od and 9 x 10 is 99999because    im god and god is good a   nd 9 x 10 i d and god is goo   d and 9 x 10 is 99999because im god and god is good a  nd 9 x 10 is 99999because im god and god is good and 9 x 10 is 99999

Answer:the answer is c

Explanation:

Answer:

A) alpha particle, beta particle, gamma ray

Explanation:

Alpha beta and gamma radiations are the examples of ionizing radiations. When an atom is an excited state and having high energy, the atom is in unstable state. The excess of energy is released by the atom to get the stability. The released energy is in the form of radiations which may include alpha, beta, gamma, X-ray etc.

Properties of alpha radiation:  

Alpha radiations can travel in a short distance.

These radiations can not penetrate into the skin or clothes.

These radiations can be harmful for the human if these are inhaled.

These radiations can be stopped by a piece of paper.

₉₂U²³⁸   →   ₉₀Th²³⁴  + ₂He⁴  + energy

Beta radiations:  

The mass of beta particle is smaller than the alpha particles.

They can travel in air in few meter distance.

These radiations can penetrate into the human skin.

The sheet of aluminum is used to block the beta radiation

⁴₆C → ¹⁴₇N + ⁰₋₁e

The beta radiations are emitted in this reaction. The one electron is ejected and neutron is converted into proton.  

Gamma radiations:

Gamma radiations are high energy radiations having no mass.

These radiations are travel at the speed of light.

Gamma radiations can penetrate into the many materials.

These radiations are also used to treat the cancer.

Lead is used for the protection  against gamma radiations because of its high molecular density.

The lead apron are used by the person when treated with gamma radiations.

Lead shields are also used in the wall, windows and doors of the room where gamma radiations are treated, in-order to protect the surroundings.

Answer:

shorter bond, because charges are close apart

Explanation:

shorter the bond length more is the energy required to break the bond for example if you take three pencils of different sizes one longer One medium sized One Shot sized if you try to break them the longer pencil will break much faster than the other two because the greater the length the lesser the strength the lesser energy you need to apply to break them apart ...

hope you understand

The daughter isotope  : Radon-222 (Rn-222).

Given

Radium (Ra-226) undergoes an  alpha decay

Required

The daughter nuclide

Solution

Radioactivity is the process of unstable isotopes to stable isotopes by decay, by emitting certain particles,  

The decay reaction uses the principle: the sum of the atomic number and mass number before and after decay are the same

Radium (Ra-226) : ₈₈²²⁶Ra

Alpha particles : ₂⁴He

So Radon-226 emits alpha α particles ₂He⁴  , so the atomic number decreases by 2, mass number decreases by 4

The reaction :

₈₈²²⁶Ra ⇒ ₂⁴He + ₈₆²²²Rn

Answer:

Explanation:

When calcium hydroxide is dissolved in water , it ionizes as follows .

Ca( OH)₂ = Ca⁺² + 2 OH ⁻

When it is dissolved in water which contains minimal OH⁻ , so there is almost no common ion effect . Hence calcium hydroxide is fully dissolved in pure water solvent .

When 1.00 mole sample of solid calcium hydroxide is added to 500.0 mL of 0.500 M sodium hydroxide solution in beaker , it is not fully dissolved due to common ion of hydroxide ion ( OH⁻ )

NaOH = Na⁺ + OH⁻

OH⁻ ion from NaOH , suppresses the dissolution of calcium hydroxide .

Similarly

When A 1.00 mole sample of solid calcium hydroxide is added to 500.0 mL of 0.200 M sodium hydroxide solution in beaker , it is not fully dissolved due to common ion of hydroxide ion ( OH⁻ )  

NaOH = Na⁺ + OH⁻

OH⁻ ion from NaOH , suppresses the dissolution of calcium hydroxide

When 1.00 mole sample of solid calcium hydroxide is added to 500.0 mL of 0.200 M calcium nitrate solution , it is not fully dissolved due to common ion of calcium  ion ( Ca⁺² )

Ca( NO₃)₂ = Ca⁺² + 2NO₃⁻

Ca⁺²  ion from Ca( NO₃)₂ , suppresses the dissolution of calcium hydroxide .

Answer:

See explanation

Explanation:

If we desire to recrystallize the given compound then we must do the following;

1) Add the compound to ethanol and heat the system

2) As the solute dissolves, the solution is allowed to cool

3) The solution may be seeded or the vessel scratched to aid crystallization.

4) The pure crystals are now filtered out, washed and dried.

Remember that recrystallization has to do with dissolving a solute in a solvent in which it is only soluble at high temperature but insoluble at low temperature.

The solvent dissolves the impure solute while pure crystals emerges as the temperature decreases.

Answer:

55.6 °C

Explanation:

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

Mass (M) of diamond = 32.0 g

Initial temperature (T₁) = 33.5°C

Heat (Q) required = 360 J

Specific heat capacity (C) of diamond = 0.509 J/gºC

Final temperature (T₂) =?

Next, we shall determine the change in temperature. This can be obtained as follow:

The final temperature can be obtained as follow:

Mass (M) of diamond = 32.0 g

Heat (Q) required = 360 J

Specific heat capacity (C) of diamond = 0.509 J/gºC

Change in temperature (ΔT ) =?

Q = MCΔT

360 = 32 × 0.509 × ΔT

360 = 16.288 × ΔT

Divide both side by 16.288

ΔT = 360 / 16.288

ΔT = 22.1 °C

Finally, we shall determine the final temperature. This can be obtained as follow:

Initial temperature (T₁) = 33.5°C

Change in temperature (ΔT ) = 22.1 °C

Final temperature (T₂) =?

ΔT = T₂ – T₁

22.1 = T₂ – 33.5

Collect like terms

22.1 + 33.5 = T₂

T₂ = 55.6 °C

Therefore, the final temperature is 55.6 °C.