Sodium-25 was to be used in an experiment, but it took 3.0 minutes to get the sodium from the reactor to the laboratory. If 8.0 mg of sodium-25 was removed from the reactor, how many mg of sodium-25 were placed in the reaction vessel 3.0 minutes later if the half life of sodium-25 is 60 seconds.

Answer:

The reactant in a chemical reaction that limits the amount of product that can be formed. The reaction will stop when all of the limiting reactant is consumed. Excess Reactant - The reactant in a chemical reaction that remains when a reaction stops when the limiting reactant is completely consumed.

Explanation:

Answer:

If two atoms have different numbers of protons, they are different elements. However, if two atoms have the same number of protons, but different numbers of neutrons we refer to them as isotopes. Two terms we use to identify nuclides (isotopes) are atomic number and mass number.

Explanation:

Your Welcome!

To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. Therefore, in below given ways we can identify isotopes.

Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.

In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron.

Differing elements exist when two atoms contain different numbers of protons. If two atoms contain the same amount of protons but differing numbers of neutrons, they are referred to be isotopes.

Therefore, in above given ways we can identify isotopes.

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Answer:

In chemistry, a single bond is a chemical bond between two atoms involving two valence electrons. That is, the atoms share one pair of electrons where the bond forms. Therefore, a single bond is a type of covalent bond.

Explanation:

(copied from Google)

Answer:

The answer to your question is given below

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

Zn + 2HCl —> ZnCl2 + H2

Thus, we can write out the atoms present in both the reactant and the product by doing a simple head count. The atoms present are listed below:

Element >>> Reactant >>> Product

Zn >>>>>>>> 1 >>>>>>>>>> 1

H >>>>>>>>> 2 >>>>>>>>> 2

Cl >>>>>>>>> 2 >>>>>>>>> 2

Answer:

Yes!

Explanation:

I think It would be fun!, Going thought space going from planet to planet. once i get back to earth i can make a document about my time in space.

a.NH₃+HCl⇒NH₄Cl

b.volume HCl=150 ml

c. pH=4.82

Reaction

NH₃+HCl⇒NH₄Cl

The equivalence point⇒mol NH₃=HCl

Titration formula :

M₁V₁n₁=M₂V₂n₂(n=acid base valence, NH₃=HCl=1)

mol NH₃

[tex]\tt 2.5\times 30=75~mlmol[/tex]

mol HCl=75 mlmol

[tex]\tt \dfrac{75}{0.5}=150~ml[/tex]

Volume total :

[tex]\tt 150+30=180~ml[/tex]

mol NH₄Cl=mol NH₃=75 mlmol=0.075 mol

[tex]\tt M=\dfrac{0.075}{0.180}= 0.42[/tex]

Dissociation of NH₄Cl at water to find [H₃O⁺]

[tex]\tt NH_4+H_2O\rightarrow NH_3+H_3O^+[/tex]

ICE at equilibrium :

0.41-x            x        x

Ka(Kw:Kb)= 10⁻¹⁴ : 1.8.10⁻⁵=5.6.10⁻¹⁰

[tex]\tt Ka=\dfrac{NH_3.H_3O}{NH_4}=\dfrac{x^2}{0.41}[/tex]

[H₃O⁺]=x :

[tex]\tt \sqrt{5.6.10^{-10}\times 0.41}=1.515.10^{-5}[/tex]

pH=-log[H₃O⁺]

[tex]\tt pH=5-log~1.515=4.82[/tex]

Answer:

i just took the test the correct answer is   "most of them stay green all year"

Explanation:

Answer:

its B :)

Explanation:

cuz im mr beast

Answer:

Not sure if you just wanted the basic structure or full on structure.

Explanation:

the answer is electrons.....

Answer:

electrons

Explanation:

Answer:

T(final) = 52°C

Explanation:

1st, you need to correct your heat flow formula => q = mcΔT.

m = 22.5g

c = 0.45 j/g·°C

ΔT = T(final) - T(initial) = T(final) - 20°C

q = (22.5g)(0.45j/g·°C)((final) - 20°C) = 324j

=> T(final) = [324j/(22.5g)(0.45j/g·°C)] + 20°C = 52°C

Answer:

HNO₂ ⇄ H⁺ + NO₂⁻

Ka = 4.0 × 10⁻⁴

Explanation:

Step 1: Given data

Step 2: Write the acid dissociation reaction

Nitrous acid is a weak acid that dissociates according to the following expression.

HNO₂ ⇄ H⁺ + NO₂⁻

Step 3: Calculate the concentration of H⁺

We will use the definition of pH.

pH = -log [H⁺]

[H⁺] = antilog - pH = antilog -2.70 = 2.00 × 10⁻³ M

Step 4: Calculate the acid dissociation constant (Ka)

For a weak acid, we can calculate Ka using the following expression.

Ka = [H⁺]²/Ca

Ka = (2.00 × 10⁻³)²/0.010

Ka = 4.0 × 10⁻⁴

Answer:a a atom

Explanation:

Answer:

a. carbon

b. atomic number

c. mass number

d. 6

e. 7

f. 8

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Answer:

Explanation:

The new volume can be found by using the formula for Boyle's law which is

[tex]P_1V_1 = P_2V_2[/tex]

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume

Since we are finding the new volume

[tex]V_2 = \frac{P_1V_1}{P_2} \\[/tex]

So we have

[tex]V_2 = \frac{5 \times 40}{1} \\ = 5 \times 40[/tex]

We have the final answer as

Hope this helps you

Answer:

The answer is "Option b, c, and d".

Explanation:

In such a gene, Autosomes are also the sequence for code and transposable elements, not the series of encoding. Through the expression of genes, such fragments of its introns are split through protein complexes throughout the translation process. There has been no kenaf fiber in the genomes of prokaryotic cells.

To calculate the atoms of an element in a given molecule, we need to multiply stoichiometry by the number that is written on the foot of that element. Therefore, the products are carbon dioxide, sulfur dioxide and water.

Balanced equation is the one in which the total number of atoms of a species on reactant side is equal to the total number of atoms on product side. The mass of the overall reaction should be conserved. There are so many types of chemical reaction reaction like combination reaction, displacement reaction.

The other characteristic of balanced equation is that physical state should be written with each compound or molecule on reactant and product side. Physical state should be written in brackets. s means solid, l means liquid, g means gas.

The balanced equation is

CH[tex]_3[/tex]SH + 4O[tex]_2[/tex] → CO[tex]_2[/tex] + SO[tex]_2[/tex] +2H[tex]_2[/tex]O

The products that are formed in the given reaction are carbon dioxide, sulfur dioxide and water.

Therefore, the products are carbon dioxide, sulfur dioxide and water.

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Answer:

answer is d Combining

Explanation:

I did the test and got it correct

As a chemical change takes place when binders are added to a paint mixture combining part of the manufacturing process occurs.

Chemical changes are defined as changes which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical change.

There are several characteristics of chemical changes like change in color, change in state , change in odor and change in composition . During chemical change there is also formation of precipitate an insoluble mass of substance or even evolution of gases.

There are three types of chemical changes:

1) inorganic changes

2)organic changes

3) biochemical changes

During chemical changes atoms are rearranged and changes are accompanied by an energy change as new substances are formed.

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Answer:

1.43 (w/w %)

Explanation:

HCl reacts with NH3 as follows:

HCl + NH3 → NH4+ + Cl-

1 mole of HCl reacts per mole of ammonia.

Mass of NH3 is obtained as follows:

Moles HCl:

0.02999L * (0.1068mol / L) = 3.203x10-3 moles HCl = Moles NH3

Mass NH3 in the aliquot:

3.203x10-3 moles NH3 * (17.031g / mol) = 0.0545g.

Mass of sample + water = 22.225g + 75.815g = 98.04g

Dilution factor: 98.04g / 14.842g = 6.6056

That means mass of NH3 in the sample is:

0.0545g * 6.6056 = 0.36g NH3

Weight percent is:

0.36g NH3 / 25.225g * 100

Answer:

A: COAL

Explanation:

Coal was created hundreds of millions years ago. When prehistoric plant life died and sank to the bottom of the swamp and was covered by layers of sediment.

Answer:

be.77.0kj.

Explanation:

add moles then times

Considering the definition of enthalpy of vaporization,  the correct answer is option c. the heat required to vaporize 15.8 g of CH₃OH at its boiling point is 18.8 kJ.

When a material changes phase from solid to liquid, or from liquid to gas, a certain amount of energy is involved in this phase change.

In case of phase change from liquid to gas, this amount of energy is known as enthalpy of vaporization (symbolized as ∆H vap), also known as (latent) heat of vaporization or heat of evaporation.

In other words, the enthalpy of vaporization is the amount of energy required to change a unit of mass (for example, moles or kg) of a substance from phase liquid to phase gas at constant temperature and pressure.

In this case, you know that enthalpy of vaporization is ∆Hvap = 38.0 kJ/mol.

On the other side, you want to vaporize 15.8 g of CH₃OH.  Then, being the molar mass of the compound 32 g / mole (that is, the amount of mass contained in one mole), the number of moles to be vaporized is:

[tex]15.8 gramsx\frac{1 mol}{32 grams}= 0.49375 moles[/tex]

Then, the heat required to vaporize 0.49375 moles of CH₃OH at its boiling point is calculated taking into account the enthalpy of vaporization by:

0.49375 moles×  38.0 kJ/mol= 18.76 kJ ≅ 18.8 kJ

Finally, the correct answer is option c. the heat required to vaporize 15.8 g of CH₃OH at its boiling point is 18.8 kJ.

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Answer:

Based on what you have seen in the Doppler Effect Gizmo, what is the best definition of the Doppler effect? A change in the frequency of a wave caused by the motion of the source relative to the observer. The increase in volume of a sound as the source approaches an observer.

Explanation:

Answer:

[H₃O⁺] = 0.0507 M

pH = 1.29

Explanation:

23.1 g of HCI (a strong acid) is added to water to make 1250 mL of solution. Calculate [H₃O⁺] and pH of the solution.

Step 1: Given data

Step 2: Calculate the concentration of HCl

We will use the following expression.

[HCl] = mass HCl / molar mass HCl × liters of solution

[HCl] = 2.31 g / 36.46 g/mol × 1.250 L

[HCl] = 0.0507 M

Step 3: Calculate the concentration of H₃O⁺

HCl is a strong acid according to the following equation.

HCl(aq) + H₂O(l) ⇒ H₃O⁺(aq) + Cl⁻(aq)

The molar ratio of HCl to H₃O⁺ is 1:1. Then, [H₃O⁺] = 0.0507 M.

Step 4: Calculate the pH of the solution

We will use the following expression.

pH = -log [H₃O⁺]

pH = -log 0.0507

pH = 1.29

Answer:

0.83 bar

That is

23/300*100

=0.83 bar

Answer:

Explanation:

Sr(OH)₂.+ 2HCl = SrCl₂ + 2H₂O

Moles of HCl in 28mL of .10 M HCl = .028 x .1 = .0028 moles .

Moles of Sr(OH)₂ in 60mL of .10 M Sr(OH)₂ = .060 x .1 = .0060 moles

2 moles of HCl  reacts with 1 mole of Sr(OH)₂

.0028 moles of HCl  reacts with .0014  mole of Sr(OH)₂

moles of Sr(OH)₂ remaining = .0060 - .0014 = .0046 moles .

Sr(OH)₂  = Sr⁺  +  2OH⁻

1 mole                  2 mole

.0046                    .0092

Total volume of solution = 88 mL .

88 mL of solution contains .0092 moles of OH⁻

concentration of OH⁻ = .0092 / .088

= .1045 M  .

When Strontium hydroxide, Sr(OH)₂ will react with hydrochloric acid (HCl) then the reaction formed will be:

Sr(OH)₂+ 2 HCl ⇒ SrCl₂ + 2 H₂O

The concentration of OH in the resulting solution will be 0.1045 M.

This can be calculated by:

[tex]\text{Molarity} = \dfrac{\text{moles}}{\text{volume of the solution in litres}}[/tex]

Moles of HCl = 0.028 x 0.1 = 0.0028 moles

Moles of Sr(OH)₂ =  0.060 x 0.1 = 0.0060 moles

Remaining moles of Sr(OH)₂  = 0.0060 - 0.0014 = 0.0046 moles

Sr(OH)₂   ⇒   Sr⁺ + 2OH⁻

1 mole                    2 mole

0.0046                  0.0092

Total volume of solution = 88 mL

88 mL of solution contains 0.0092 moles of OH⁻

Hence, concentration of OH⁻ :

[tex]= \dfrac{0.0092 }{0.088}[/tex]

= 0.1045 M

Therefore, 0.1045 M will be the concentration of OH in the solution.

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Answer:

you cant post pictures on brainly answers.... can you?

Explanation:

The diagram is correct because electrons are present in distinct energy levels around the nucleus. Option D

Let nus just take a minute to be able to remind ourselves that when we look at the atom that there are several subatomic particles that can be shown to be able to make up the atom. We know that the electron is the particle that can be shown to be arranged in shells.

What we saw in the inner or the core of the atom is the nucleus and the six grey spheres  that we can see there would have to do with the nucleus of the atom that is in the question.

As we now look up at the shells, we can see the electrons as they have been arranged into the respective shells were they can be found in the atom on the basis of the energy that they possess.

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Liquid 2 because the lower the density the more it floats and the higher the density the more it sinks. The order from top to bottom is liquid 2, liquid 3, liquid 1

Answer:

sulfide ion

Explanation:

however, when non-metalic elements gain electrons to form anions the end of their name is change to "-ide".foe example, a flourin atom gains one electronto become a flouride ion(F`) and sulfur gains two electrons to become a sulfide ion(s^2)