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Answer:

28.085

Explanation:

The formular to obtain average atomic mass unit from isotopes is given as;

sum of (Percentage abundance * Atomic mass) of all isotopes =  Average atomic mass unit

Silicon 28 = 92.23%

Silicon 29 = 4.67%

Silicon 30 = 3.1%

(92.23 / 100  *  27.977) + (4.67 / 100  *  28.976)  +  (3.1 / 100  * 29.974) = Average atomic mass

Average atomic  mass = 25.803 + 1.353 + 0.929 = 28.085

Answer:

A double covalent bond

Explanation:

A double covalent bond is a situation where we have two pairs of electrons shared together between the atoms instead of just one pair. Oxygen gas is an example of a simple molecule that contains double bonds.

In other words, it is a type of chemical bond that has 2 electron pairs shared between two atoms.

Answer:

The options are

A. a hypothesis

B. a theory

C. a research question

D. a scientific explanation

The answer is A. a hypothesis

Explanation:

A hypothesis is referred to as a brief explanation on the occurrence of an event.

In the example above using of warm water on plants was inferred to make it grow faster as hot water increases the metabolism.

Answer:

The answer is C

Explanation:

2.2.2: The pH Scale

pOH = -log[OH-]

Answer:

a. 2 HgO(s) ⇒ 2 Hg(l) + O₂(g)

b. 0.957 g

Explanation:

Step 1: Write the balanced equation

2 HgO(s) ⇒ 2 Hg(l) + O₂(g)

Step 2: Convert 130.0 °C to Kelvin

We will use the following expression.

K = °C + 273.15

K = 130.0°C + 273.15

K = 403.2 K

Step 3: Calculate the moles of O₂

We will use the ideal gas equation.

P × V = n × R × T

n = P × V/R × T

n = 1 atm × 0.0730 L/0.0821 atm.L/mol.K × 403.2 K

n = 2.21 × 10⁻³ mol

Step 4: Calculate the moles of HgO that produced 2.21 × 10⁻³ moles of O₂

The molar ratio of HgO to O₂ is 2:1. The moles of HgO required are 2/1 × 2.21 × 10⁻³ mol = 4.42 × 10⁻³ mol.

Step 5: Calculate the mass corresponding to 4.42 × 10⁻³ moles of HgO

The molar mass of HgO is 216.59 g/mol.

4.42 × 10⁻³ mol × 216.59 g/mol = 0.957 g

Answer: Sorry I try to download it but it not showing anything, if you take a picture of the work maybe I would do it....

Explanation:

Answer:

Density = 11.4 g/cm³

Explanation:

Given data:

Density of lead = ?

Height of lead bar = 0.500 cm

Width of lead bar = 1.55 cm

Length of lead bar = 25.00 cm

Mass of lead bar = 220.9 g

Solution:

Density = mass/ volume

Volume of bar = length × width × height

Volume of bar = 25.00 cm × 1.55 cm × 0.500 cm

Volume of bar = 19.4 cm³

Density of bar:

Density = 220.9 g/ 19.4 cm³

Density = 11.4 g/cm³

Answer:

12.5

Explanation:

Step 1: Write the balanced equation

2 NO₂(g) ⇄ N₂O₄(g)

Since the reaction takes place in a 1.00 L vessel, the initial concentration of NO₂ is 0.0300 M and the concentration at equilibrium of N₂O₄ is 0.00500 M.

Step 2: Make an ICE chart

        2 NO₂(g) ⇄ N₂O₄(g)

I          0.0300        0

C           -2x            +x

E     0.0300-2x        x

Step 3: Find the value of x

Since [N₂O₄]eq = 0.00500 M, x = 0.00500

Step 4: Calculate the concentrations at equilibrium

[NO₂] = 0.0300-2(0.00500) = 0.0200 M

[N₂O₄] = 0.00500 M

Step 5: Calculate the concentration equilibrium constant (Kc)

Kc = [N₂O₄]/[NO₂]²

Kc = 0.00500/0.0200²

Kc = 12.5

Answer:

The lungs

Explanation:

Asthma is a disease that affects the airways of your lungs. With asthma, your airways' lining tends to always be in a hypersensitive state characterized by redness and swelling. Causing the airways to swell and, in severe cases, close completely off.

hope this helps, this should also probably be in biology:)

Answer:

[tex]84.94\ \text{mL}[/tex]

Explanation:

[tex]m[/tex] = Mass of ethyl alcohol = [tex]67.1\ \text{g}[/tex]

[tex]\rho[/tex] = Density of ethyl alcohol = [tex]0.79\ \text{g/mL}[/tex]

[tex]V[/tex] = Volume of ethyl alcohol

Density is given by

[tex]\rho=\dfrac{m}{V}\\\Rightarrow V=\dfrac{m}{\rho}\\\Rightarrow V=\dfrac{67.1}{0.79}\\\Rightarrow V=84.94\ \text{mL}[/tex]

The volume of ethyl alcohol is [tex]84.94\ \text{mL}[/tex].

Answer:

In this Lewis equation it can be seen how oxygen and hydrogen have a dative union, that is, there is a proton that is temporarily "borrowed"

Explanation:

This molecule is the same as water but with one more hydrogen, that is why the general charge of the molecule is positive

Answer:

13.33g/mL is mercury's density

Explanation:

The density of a substance is defined as the ratio between the mass of the substance and the space that occupy. We can express the density of mercury in g/mL:

Grams mercury: 685.0g

Volume = 51.39mL

That means the density of the mercury is:

685.0g / 51.39mL

Answer:

You can heat it and then let it cool it in a very strong magnetic field.

It can be heated and then allowed to cool in a very powerful magnetic field. To make an item that is made of magnetic material become a permanent magnet instead of a temporary magnet.

The magnetic influence on moving electric charges, electric currents, and magnetic materials is described by a magnetic field, which is a vector field. A force perpendicular to the charge's own velocity and the magnetic field acts on it when the charge is travelling through a magnetic field.

Heating a ferromagnetic material to a crucially high temperature is the primary method for producing permanent magnets. Although the temperature varies depending on the type of metal, it has the effect of aligning and "fixing" the magnet's domains in place over time.

Electric charges in motion are what generate magnetism. The smallest building blocks of matter are called atoms. Each atom contains electrons, which are tiny particles with electric charges.

Thus, It can be heated and then allowed to cool in a very powerful magnetic field.

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Answer:

Sodium carbonate, Na₂CO₃ is the limiting

Explanation:

We'll begin by writing the balanced equation for the reaction between iron (iii) chloride, FeCl₃ and sodium carbonate, Na₂CO₃.

This is illustrated below:

2FeCl₃ + 3Na₂CO₃ → Fe₂(CO₃)₃ + 6NaCl

Next, we shall determine the masses of FeCl₃ and Na₂CO₃ that reacted from the balanced equation. This can be obtained as follow:

Molar mass of FeCl₃ = 56 + (3×35.5)

= 56 + 106.5

= 162.5 g/mol

Mass of FeCl₃ from the balanced equation = 2 × 162.5 = 325 g

Molar mass of Na₂CO₃ = (2×23) + 12 + (3×16)

= 46 + 12 + 48

= 106 g/mol

Mass of Na₂CO₃ from the balanced equation = 3 × 106 = 318 g

SUMMARY:

From the balanced equation above,

325 g of FeCl₃ reacted with 318 g of Na₂CO₃.

Finally, we shall determine the limiting reactant. This can be obtained as follow:

From the balanced equation above,

325 g of FeCl₃ reacted with 318 g of Na₂CO₃.

Therefore, 34.5 g of FeCl₃ will react with = (34.5 × 318)/325 = 33.76 g of Na₂CO₃.

From the calculations made above, we can see clearly that it will take a higher amount (i.e 33.76 g) of Na₂CO₃ than what was given (i.e 25.3 g) to react completely with 34.5 g of FeCl₃. Therefore, Na₂CO₃ is the limiting reactant and FeCl₃ is the excess reactant.

Answer:

0.56 g

Explanation:

A chemist determines by measurements that 0.020 moles of nitrogen gas participate in a chemical reaction. Calculate the mass of nitrogen gas that participates.

Step 1: Given data

Moles of nitrogen gas (n): 0.020 mol

Step 2: Calculate the molar mass (M) of nitrogen gas

Molecular nitrogen is a gas formed by diatomic molecules, whose chemical formula is N₂. Its molar mass is:

M(N₂) = 2 × M(N) = 2 × 14.01 g/mol = 28.02 g/mol

Step 3: Calculate the mass (m) corresponding to 0 0.020 moles of nitrogen gas

We will use the following expression.

m = n × M

m = 0.020 mol × 28.02 g/mol

m = 0.56 g

Answer:

Explanation:

18 gram of water contains 2 g of hydrogen

3.123 gram of water will contain 2 x 3.123 / 18 = .347 g of hydrogen .

44 gram of carbon dioxide contains 12 g of carbon

7.691 gram of carbon dioxide will contain 12 x 7.691 / 44 = 2.1 g of carbon .

So the sample will contain 2.912 - ( .347 + 2.1 ) g of oxygen .

= .465 g of oxygen .

moles of Carbon = 2.1 / 12 = .175

moles of hydrogen = .347 / 1 = .347

moles of oxygen = .465 / 16 = .029

Ratio of moles of carbon , oxygen and hydrogen ( C,O,H )

= 0.175 : 0.029 : 0.347

= .175/ .029 : 1 : .347 / .029

= 6 : 1 : 12

So empirical formula = C₆H₁₂O

Let the molecular formula be [tex](C_6H_{12}O)_n[/tex]

molecular weight = n ( 6 x 12 + 12x 1 + 16)

= 100 n

Given 100 n = 100.1

n = 1

Molecular formula = C₆H₁₂O.

Answer:

0.20

Explanation:

Step 1: Write the balanced equation

2 SO₂(g) + O₂(g) ⇄ 2 SO₃(g)

Step 2: Make an ICE chart

        2 SO₂(g) + O₂(g) ⇄ 2 SO₃(g)

I            3.9         3.2              0

C          -2x          -x             +2x

E        3.9-2x     3.2-x            2x

Step 3: Find the value of x

The partial pressure at equilbrium of SO₃ is 1.6 atm. Then,

2x = 1.6 atm

x = 0.80 atm

Step 4: Calculate the partial pressures at equilibrium

pSO₂ = 3.9-2(0.80) = 2.3 atm

pO₂ = 3.2-0.80 = 2.4 atm

pSO₃ = 1.6 atm

Step 5: Calculate the pressure equilibrium constant

Kp = pSO₃² / pSO₂² × pO₂

Kp = 1.6² / 2.3² × 2.4

Kp = 0.20

Answer:

1.005 x [tex]10^{1}[/tex]

Explanation:

Answer:

C₄H₁₀O₄

Explanation:

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

Mass of compound = 4 g

Molar mass of compound = 152 g/mol

Mass of CO₂ = 5.79 g

Mass of H₂O = 2.84 g

Molecular formula of compound X =?

Next, we shall determine the mass of Carbon, Hydrogen and Oxygen in the compound. This can be obtained as follow:

For Carbon (C):

Mass of CO₂ = 5.79 g

Molar mass of CO₂ = 12 + (2×16) = 44 g/mol

Mass of C = 12/44 × 5.79

Mass of C = 1.58 g

For Hydrogen (H):

Mass of H₂O = 2.84 g

Molar mass of H₂O = (2×1) + 16 = 18 g/mol

Mass of H = 2/18 × 2.84

Mass of H = 0.32 g

For Oxygen (O):

Mass of C = 1.58 g

Mass of H = 0.32 g

Mass of compound = 4 g

Mass of O =?

Mass of O = (Mass of compound) – (Mass of C + Mass of H)

Mass of O = 4 – (1.58 + 0.32)

Mass of O = 4 – 1.9

Mass of O = 2.1 g

Next, we shall determine the empirical for compound X. This can be obtained as follow:

C = 1.58 g

H = 0.32 g

O = 2.1 g

Divide by their molar mass

C = 1.58 / 12 = 0.13

H = 0.32 / 1 = 0.32

O = 2.1 / 16 = 0.13

Divide by the smallest

C = 0.13 / 0.13 = 1

H = 0.32 / 0.13 = 2.46

O = 0.131 / 0.13 = 1

Multiply by 2 to express in whole number

C = 1 × 2 = 2

H = 2.46 × 2 = 5

O = 1 × 2 = 2

Thus, the empirical formula for the compound is C₂H₅O₂

Finally, we shall determine the molecular formula for the compound. This can be obtained as follow:

Molar mass of compound = 152 g/mol

Empirical formula => C₂H₅O₂

Molecular formula =?

Molecular formula => [C₂H₅O₂]ₙ

[C₂H₅O₂]ₙ = 152

[(2×12) + (5×1) + (2×16)]n = 152

[24 + 5 + 32]n = 152

61n = 152

Divide both side by 61

n = 152 / 61

n = 2

Molecular formula => [C₂H₅O₂]₂

Molecular formula => C₄H₁₀O₄

Answer:

3.09 atm

Explanation:

Given that:

Volume of container A = 717 mL

Pressure of container A = 2.80 atm

Volume of container B = 174 mL

Pressure of container B = 4.30 atm

Now, if the valve are being removed and the gases are allowed to mix together; then

The total final pressure can be calculated by using the formula:

[tex]P_f = \dfrac{P_AVA+P_BV_B}{V_A+V_B}[/tex]

[tex]P_f = \dfrac{2.80*717+4.30*174}{717+174}[/tex]

[tex]P_f = \dfrac{2007.6+748.2}{891}[/tex]

[tex]P_f = \dfrac{2755.8}{891}[/tex]

[tex]\mathbf{P_f =3.09 \ atm}[/tex]

The absence of the intermolecular attraction between the atoms or molecules is called an ideal gas.  The pressure of the resultant mixture is 3.09 atm.

The relationship between the pressure and the volume of the gas is given by Boyle's law which states the inverse proportionality relation with the volume.

Given,

The volume of container A = 717 mL

The volume of container B = 174 mL

The pressure of container A = 2.80 atm

The pressure of container B = 4.30 atm

The total final pressure of the ideal gas of the mixture is calculated by:

[tex]\begin{aligned} \rm P_{f} &= \rm \dfrac{P_{A}V_{A}+ P_{B}V_{B}}{V_{A}+V_{B}}\\\\&= \dfrac{2007.6 +748.2}{891}\\\\&= 3.09 \;\rm atm\end{aligned}[/tex]

Therefore, the total pressure of the mixture is 3.09 atm.

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Answer:

A. A solid mixture is heated. One component transitions directly between solid and gas ---> Sublimation

B. A liquid is carefully poured out, leaving the solid behind in the container ----> Decantation

C. A solvent is added to dissolve only one mixture component and then the liquids are separated ----> solvent extraction

D. A solid is caught on paper or a membrane while the liquid passes through ---> Filtration using filter paper

Explanation:

A. Sublimation is a process of separating solids which sublimes (solids turning directly to gases) from a a mixture of other solids which do not sublime. When the mixture is heated, the solids which sublime are separated and those which do not are left behind. examples of solids which sublime are naphthalene, Iodine crystals, etc.

B. Decantation is the process of carefully pouring out a liquid from a mixture of it with a solid, leaving the solid behind. Example, a mixture of sand and water where water can be easily decanted, leaving the sand behind.

C. In the process of solvent extraction, a mixture of solids which are soluble in different solvent, one of the components is dissolved in a solvent in which it is soluble while the others are not. The solution is then filtered out and the solid is then separated from the solvent by evaporation.

D. In filtration using a filter paper, the solid-liquid mixture is passed through a filter paper which has pores the size through which liquids can pass through but the solid can not. therefore, the solid remains behind on the paper while the liquid passes through.

A is sublimation, B is decantation, C is solvent extraction, and D is filtration.

Chemical mixtures are separated in different ways.

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Dry ice are the molecule which represent molecular solid. Hence option c is correct.

Molecules are defined as  the lowest identifiable unit into which a pure material can be divided while maintaining its chemical makeup and attributes is made up of two or more atoms. When two or more atoms come together and form bonds with one another, a molecule is created. Each atom shares an electron when a bond is formed between them. A molecule is created as a result of a covalent bond.

Molecular solid are defined as composed of atoms or molecules joined by hydrogen bonds, London dispersion forces, and dipole-dipole forces. Solids made of molecules and held together by van der Waals forces are referred to as molecular solids. Examples include carbon dioxide, hydrogen, etc. Crystalline solids include ZnS. The ionic solid MgO is. Diamond is organized in a network.

Thus, dry ice are the molecule which represent molecular solid. Hence option c is correct.

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Your question is incomplete,  but probably your complete question was

Which of the following is an example of molecular solid?

a. Zinc sulphide

b. Magnesium oxide

c. Dry ice

d. Diamond

Answer:

Check the explanation section.

Explanation:

The following steps should be followed orderly.

STEP ONE:

Use the dilution equation in the calculation of the volume for the stock solution. That is, C1 × V1 = C2 × V2.

Where C1 and C2 are the concentration of the stock solution and the diluted solution.

STEP TWO:

Put 6% of lactose and make sure to dilute it in order to make 2.0% lactose

and put it in Beaker A. Also, make sure to dilute the 1M to 0.1M SPG buffer in Beaker B.

STEP TWO:

Now, from beaker A containing 2% lactose, measure and remove 5.0 mL from it. Also, measure and remove 5.0 mL from beaker B containing 0.1M SPG.

So, in STEP TWO above we won't know how much water we need to use for dilution, thus, there is the need to make use of STEP ONE.

Therefore, from STEP ONE ABOVE, we have the dilution equation given as;

C1 × V1 = C2 × V2.

Hence, 6 × V1 = 2 × 5. Therefore, the volume needed from the stock solution, V1 = (2 × 5)/ 6 = 1.6 mL.

STEP THREE:

Now measure out 1.6 mL from the stock solution, that is 6% lactose and add it to 5mL of the diluted solution of 2% in beaker A into another container, say beaker C and add H2O to form SOLUTION X.

STEP FOUR:

Using the dilution equation again, Determine the the volume that is needed from 1M SPG.

C1 × V1 = C2 × V2.

V1 = ( 0.1 × 5)/ 1 = 0.5mL.

STEP FIVE:

measure 0.5mL out from the 1M SPG and 5 mL out of 0.1M SPG buffer and add water to it to form SOLUTION Y.

STEP SIX:

Now, mix solution X and solution Y together and take the required 5ml

Answer: 1.6x10^22

Explanation: H2O —> H2 + 1/2O2 so half the number of water molecules

Answer: 20.775 g S

Explanation: 3.9x10^23 atoms = 0.648 mol

Atomic mass S = 32.08

S in grams = 20.775

Answer:

[tex]m=1,182.8g[/tex]

Explanation:

Hello!

In this case, since the relationship between molecules and mass is first analyzed via the Avogadro's number to compute the moles in the given molecules:

[tex]mol=4.63x10^{24}molec*\frac{1mol}{6.022x10^{23}molec}=7.69mol[/tex]

We now use the molar mass of carbon tetrachloride (153.81 g/mol) to obtain the required grams:

[tex]m=7.69mol*\frac{153.81g}{1mol} \\\\m=1,182.8g[/tex]

Best regards!

Answer:

Molecules

Explanation: