The half-life for a 400-gram sample of radioactive element X is 3 days. How much of element X remains after 15 days have passed?

A.
12.5 g

B.
25 g

C.
50 g

D.
100 g

Answer:

3.67

Explanation:

Step 1: Write the balanced equation

CO₂(g) + H₂(g) = CO(g) + H₂O(g)

Step 2: Calculate the value of the pressure equilibrium constant (Kp)

The concentration equilibrium constant (Kc) is 3.67.

We can calculate the value of the pressure equilibrium constant using the following expression.

[tex]Kp = Kc \times (R \times T)^{\Delta n(g)}[/tex]

where,

R: ideal gas constant

T: absolute temperature

Δn(g): moles of gaseous products - moles  of gaseous reactants

Δn(g) = 2 mol - 2 mol = 0

Then,

Kp = Kc × (R × T)⁰ = Kc = 3.67

Answer:

3.92%

Explanation:

The solution that is formed is of KCl in water. This means that the percent composition by mass is given by the formula:

We now calculate the mass of solution:

Finally we calculate the percent composition:

Answer:

10.5 L of O₂.

Explanation:

We'll begin by calculating the number of mole in 90 g of C₂H₆. This can be obtained as follow:

Molar mass of C₂H₆ = (12×2) + (6×1)

= 24 + 6

= 30 g/mol

Mass of C₂H₆ = 90 g

Mole of C₂H₆ =?

Mole = mass / molar mass

Mole of C₂H₆ = 90 / 30

Mole of C₂H₆ = 3 moles.

Finally, we shall determine the volume of O₂ required. This is illustrated:

2C₂H₆ + 7O₂ —> 4CO₂ + 6H₂O

From the balanced equation above, we can say that:

2 L of C₂H₆ required 7 L of O₂.

Therefore, 3 L of C₂H₆ will require

= (3 × 7)/ 2 = 10.5 L of O₂.

Thus, 10.5 L of O₂ is required for the reaction.

Answer:

solution given:

log k=4-[tex] \frac{200}{t} [/tex]

so,

On comparison

∆S°/R = 4

∆ S° = 4R

mousam brother is correct

hope it helps you have a good day

Answer:

0.0010 M of HC2H302(aq)

Answer:

Volume is reduced to half

Explanation:

Acid base titration are commonly used reactions in a lab, and are ofter used to get pH or different kind of solutions.

The neutralization of an acid base reaction is reached, when the solution (having added an indicator previously) changes its original color. chemically speaking, this occurs when the number of moles of the acid and the base are balanced and equal. In other words the following:

n₁ = n₂   (1)

This expression can also be expressed in function of concentration and volume:

M₁V₁ = M₂V₂   (2)

From here, solving for V₁:

V₁ = M₂V₂  / M₁

Now, this expression is true only when we have the same kind of substance that can lose or gain the same number of hydrogens.

Lets suppose that we have as base NaOH (Monoprotic base) and HCl (monoprotic acid), the titration reaction would be:

NaOH + HCl --------> NaCl + H₂O

As both of the species are monoprotic, the number of moles are the same  when they reach the equilibrium, so, expression  (2) can be used, and calculate volume or concentrations.

However, in this case, a partner made a mistake and use a diprotic acid, in this case, H₂SO₄, In this case, things chance because H₂SO₄ is diprotic, meaning that we need to dissociate two hydrogens in equilibrium, therefore, expression (2) would be something like this.

Acid: 1; Base: 2

H₂SO₄ + 2NaOH ------> Na₂SO₄ + H₂O

nH₂SO₄ = n₁ = 1

nNaOH = n₂ = 2

n₁/n₂ = 1/2

2n₁ = n₂   (3)

Writting this, in function of concentration and volume, it would be:

2M₁V₁ = M₂V₂   (4)

From here, if we solve for the volume of the acid (V₁):

V₁ = M₂V₂ / 2M₁

Therefore, according to this expression, we can see that the volume required of the acid would be half the volume required of the monoprotic acid. For example, if we need 50 mL of Chloridic acid to reach the equivalence point with NaOH, then, with H₂SO₄ it will only need 25 mL. This, of course, assuming that concentrations are the same, and volume of the base used, the same.

Hope this helps

Answer:

ch3

Explanation:

Explanation:

Recommendations:

1.To make strict rules and regulations against those who violates rights

2.To mobilize police actively to stop such incidents

3.To raise public awareness to prevent human rights violation

Answer: Hewo, there!

All of the above wold be my answer

Explanation:

Although many factors combine to influence weather, the four main ones are solar radiation, the amount of which changes with Earth's tilt, orbital distance from the sun and latitude, temperature, air pressure and the abundance of water.

Hope this helps you!!

Have a great day

The reaction in which carbon combines with sulfur to form carbon

disulfide. Is

In a chemical reaction, bonds between molecules of the reactant are broken and new bonds between molecules of the product are established to create a new substance.

Chemical reactions occur all around us, including in our body's digestion of food and the creation of the sunlight's light. Understanding physical and chemical changes is crucial before starting any chemical reactions.

Sulfur and carbon combine to form carbon disulfide in an endothermic reaction that absorbs 92 kJ/mol of heat.

Learn more about carbon disulphide at:

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Answer:

OKAY EVERYONE STOP SAYING PANCREAS THATS WRONG

Explanation:

It is actually thyroid

Answer:

[tex]m_{NH_3}=21.6gNH_3[/tex]

Explanation:

Hello there!

In this case, in agreement to the given chemical reaction, it is possible for us to calculate the mass of NH3 required to remove 57.0 g NO via the stoichiometry based off the 4:6 mole ratio between them:

[tex]m_{NH_3}=57.0g NO*\frac{1molNO}{30.01gNO}*\frac{4molNH_3}{6molNO} *\frac{17.03gNH_3}{1molNH_3} \\\\m_{NH_3}=21.6gNH_3[/tex]

Best regards!

Answer:

i'm pretty sure its the last answer and if not its the 2nd one

Answer:

See Explanation

Explanation:

Metallic bonds involve attraction between electrons and positively charged metal ions. The metals are ionized and electrons form a sea of valence electrons. These loosely bound electrons surround the nuclei of the metals.

The presence of this sea of electrons explains the fact that metals conduct electricity and heat due to the free valence electrons.

Due to the nature of the bonding between metal atoms,metals are malleable and ductile.

Due to the strong electrostatic interaction between metal ions and electrons, the metallic bond is very strong and is very difficult to break thereby accounting for the greater strength of metals as the size of the metallic ion decreases.

By using combined gas law , volume will be 1.88 [tex]dm^{3}[/tex].

The combined gas law contains the laws of Charles, Boyle, and Gay-Lussac. When you know the pressure, volume, and temperature of a system and need to modify one of these, you can apply this law to compute the resulting unknown.

Combined gas law is expressed as:

[tex]$\frac{P_{1} V_{1}}{T_{1}}=\frac{P_{2} V_{2}}{T_{2}}$[/tex]

Calculation of volume by using combined gas law

It is given that, [tex]V_{1}[/tex] = 254[tex]dm^{3}[/tex], at STP P = 101.3 kPa and T = 273 K

Now, put the value of given data in above equation.

[tex]V_{2}[/tex] = (254[tex]dm^{3}[/tex]) (101.3 kPa) (26+273) /(150 kPa) (273)

[tex]V_{2}[/tex] = 1.88 [tex]dm^{3}[/tex].

By using combined gas law  volume will be 1.88 [tex]dm^{3}[/tex].

To know about combined gas law.

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Answer:

The answer is B

Explanation:

The answer is B because representative particles can only be atoms.

Answer:

pretty easy

Explanation:

step 1: Approach her

step 2: Ask her for something (make it look like you're lost even when you aren't)

step 3: engage in a conversation with her

step 4: you talk for hours and she give you her number

step 5: you wake up from your dream

step 6: wait you woke up

step 7: go back to dreaming again.

Answer: Girls are tough. Girls are....attitude, we all know its true.

Explanation

Best thing to start is shush when shes talking.

Answer:

The entropy increases

Explanation:

Just took the quiz

Answer:c

Explanation:yes

Domains eukarya  would this organism most likely fit.

The domain eukarya comprised of eukaryotes or organisms whose cells contain true nucleus.

It is  the largest of all groups in the classification of life. There are three domains:-

It is the domain of organism called eukaryotes. These are the organism who have a well defined nucleus and membrane bound organelles.

Hence, C) option is correct.

To know more about domain here

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Answer:

29.5 days

Explanation:

orginally 27.3 days but 29.5 days is also correct

Answer:

780 g

Explanation:

Step 1: Given data

Moles of sodium phosphate: 4.76 moles

Step 2: Calculate the mass corresponding to 4.76 moles of sodium phosphate

To convert moles to mass, we need a conversion factor. In this case, we will use the molar mass of sodium phosphate, which is 163.94 g/mol.

4.76 mol × 163.94 g/mol = 780 g

Answer:

2 NH₃(g) + 2 O₂(g) ⇒ N₂O(g) + 3 H₂O(l)   ΔH° = -684 kJ

Explanation:

Let's consider the unbalanced equation that occurs when NH₃(g) reacts with O₂(g) to form N₂O(g) and H₂O(l).

NH₃(g) + O₂(g) ⇒ N₂O(g) + H₂O(l)

We will begin balancing N atoms by multiplying NH₃(g) by 2.

2 NH₃(g) + O₂(g) ⇒ N₂O(g) + H₂O(l)

Then, we will balance H atoms by multiplying H₂O(l) by 3.

2 NH₃(g) + O₂(g) ⇒ N₂O(g) + 3 H₂O(l)

Finally, we will get the balanced equation by multiplying O₂(g) by 2.

2 NH₃(g) + 2 O₂(g) ⇒ N₂O(g) + 3 H₂O(l)

Since 342 kJ of energy are evolved for each mole of NH₃(g), and there are 2 moles of NH₃(g) in the balanced equation, the heat evolved will be2 × 342 kJ = 684 kJ. By convention, when heat is evolved, it takes a negative sign. The balanced thermochemical equation is:

2 NH₃(g) + 2 O₂(g) ⇒ N₂O(g) + 3 H₂O(l)   ΔH° = -684 kJ

Answer:

The answer is gravity and friction.

Explanation:

Answer:

412 g Cl₂

General Formulas and Concepts:

Atomic Structure

Stoichiometry

Explanation:

Step 1: Define

[Given] 3.50 × 10²⁴ molecules Cl₂

[Solve] grams Cl₂

Step 2: Identify Conversions

Avogadro's Number

[PT] Molar Mass of Cl - 35.45 g/mol

Molar Mass of Cl₂ - 2(35.45) = 70.9 g/mol

Step 3: Convert

Step 4: Check

Follow sig fig rules and round. We are given 3 sig figs.

412.072 g Cl₂ ≈ 412 g Cl₂

Answer:

1. Volume of stock required = 15 mL

Volume of water required = 485 mL

2. Volume of stock required = 5 mL

Volume of water required = 495 mL

3. Volume of stock required = 5.30 mL

Volume of water required = 494.70 mL

4. Volume of stock required = 50 mL

Volume of water required = 450 mL

Explanation:

Using the dilution formula C₁V₁ = C₂V₂

Where C₁ = initial concentration; C₂ = final concentration; V₁ = initial volume; V₂ = final volume

1. C₁ = 5 M NaCl, C₂ = 150 mM NaCl = 0.15 M NaCl

V₁ = ?; V₂ = 500 mL

V₁ = C₂V₂/C₁

V₁ = 0.15 × 500/ 5 = 15 mL

Volume of stock required = 15 mL

Volume of water required = 500 mL - 15 mL

Volume of water required = 485 mL

2. C₁ = 1 M Tris-HCl, C₂ = 50 mM Tris-HCl = 0.05 M Tris-HCl

V₁ = ?; V₂ = 500 mL

V₁ = C₂V₂/C₁

V₁ = 0.05 × 500/ 5 = 5 mL

Volume of stock required = 5 mL

Volume of water required = 500 mL - 5 mL

Volume of water required = 495 mL

3. C₁ = 95% NP-40, C₂ = 1% NP-40

V₁ = ?; V₂ = 500 mL

V₁ = C₂V₂/C₁

V₁ = 1 × 500/ 95 = 5.30 mL

Volume of stock required = 5.30 mL

Volume of water required = 500 mL - 5.30 mL

Volume of water required = 494.70 mL

4. C₁ = 1% SDS, C₂ = 10% SDS

V₁ = ?; V₂ = 500 mL

V₁ = C₂V₂/C₁

V₁ = 1 × 500/ 10 = 50 mL

Volume of stock required = 50 mL

Volume of water required = 500 mL - 50 mL

Volume of water required = 450 mL