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indicator, hope this helps :

Answer:

B

Explanation:

Because that's what is being changed into a different color.

Answer: 1075.5 mph

Explanation:anything moving at 4.78*10^4 cm/sec

equivalent to

cm —> miles = 1/1.6*10^5

sec —> hr = 1/3600

[4.78*10^4]*3600/1.6*10^5 = 1075.5 mph

Answer:

i wish i know

Explanation:

i wish i know

Answer:

What is ^ for?

Explanation:

Answer:

More exactly this number is 6.02 x 1023 10 2 3 .

Answer:

215.9 cm

Explanation:

1 foot= 30.5cm

30.5cm times 7 1/12=215.9cm

The given height of David is 7 ft, 1.0 inch, so in centimeters, the height will be 216.4 cm.

A conversion factor is a number that is used to multiply or divide one set of units into another. When converting to an equal value, the appropriate conversion factor must be used.

We must convert one unit to another in order to achieve accuracy and avoid measurement confusion.

We do not, for example, measure the length of a pencil in kilometers. In this case, one must convert kilometers (km) to centimeters (cm) (cm).

To convert feet to centimeters, multiply the given foot length by 30.48 cm.

So,

Height in cm will be = 7.1 x 30.48

Height in cm = 216.4cm

Thus, the height of David in centimeters is 216.4 cm.

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Mass O2 = = 16.832 g

Given

43 grams of potassium chlorate

Required

Mass of O2

Solution

Reaction

2KClO3 ⇒3O2 + 2KCl

Mol KClO3 :

= mass : MW

= 43 g : 122,55 g/mol

= 0.3509

From the equation, mol O2 :

= 3/2 x moles KClO3

= 3/2 x 0.3509

= 0.526

Mass O2 :

= 0.526 x 32 g/mol

= 16.832 g

Answer:

P = 0.0166 mm Hg

Explanation:

To solve this question, we need to use the Clausius Clapeyron equation, which is a commonly used expression to calculate vapour pressure at a given temperature. We have the enthalpy of vaporization of the mercury, so, let's write the equation:

Clausius Clapeyron equation:

Ln (P₂ / P₁) = (-ΔHv / R)(1/T₂ - 1/T₁)    (1)

Where:

R: universal constant of gases (8.314 J / K.mol)

P₂: Vapour pressure at 43°C (or 316 K)

P₁: Pressure of mercury at the boiling point (1 atm)

T₂: temperature at 43 °C

T₁: Boiling point of mercury (357 °C or 630 K)

As we are given the boiling point of the mercury, we can safely assume that the pressure at this point is 1 atm, becuase remember that when a sustance boils, is because it's internal pressure has reached the atmospherical pressure of 1 atm. With this clear, all we just need to do is solve for P₂. We are going to do this very slowly so you can understand the process. First let's replace the given data:

Ln (P₂ / 1) = (-59100 J/mol / 8.314 J / K.mol) (1/316 - 1/630)

Ln P₂ = -7108.49 * (3.16x10⁻³ - 1.59x10⁻³)

Ln P₂ = -7108.49 * (1.51x10⁻³)

Ln P₂ = -10.7338

P₂ = 10⁽⁻¹⁰°⁷³³⁸⁾

P₂ = 2.18x10⁻⁵ atm

We can express this value in mm Hg and it will be:

P₂ = 2.18x10⁻⁵ * 760

Hope this helps

Answer:

1. False 2.True3.True? Unsure

Explanation:

Answer:

32 days.

Explanation:

First we determine how much is made in a day.

16.50 x 4 = 66.

Next, we divide 2100 by 66 to reach our amount of days needed.

2100 / 66 = 31.818181... [81 is what repeats over and over.]

We round this up to the nearest whole number. You can't underpay, so you have to round.

The next whole number would be 32, so our answer is 32 days.

Answer:

Hope this help you

Explanation:

The answer is 261.3368. We assume you are converting between grams Barium Nitrate and mole. You can view more details on each measurement unit: molecular weight of Barium Nitrate or mol The molecular formula for Barium Nitrate is Ba(NO3)2.

Answer:

0.382

Explanation:

Answer: C ) The reactants are higher in energy than the products

Explanation:

The enthalpy that is a state variable that identifies the content of heat. Then the change of enthalpy for the exothermic reactions is negative, meaning that the energy of the products is lower than the energy of the reactants.

Answer:

hydrogen

Explanation:

In electrolysis of water, gas evolved at cathode is hydrogen

Answer:

4 orbits in the fourth period.

19 electrons in the atom from group 1 and fourth period.

Explanation:

Potassium has 19 electrons distributed in its 4 orbits

The number of periods in a periodic table, tells the number of shells or orbitals of the atoms in that row in which the electrons are filled. Thus the fourth period elements have 4 orbitals and the first element in group one of the fourth period is potassium containing 19 electrons.

All elements in a periodic table are classified into different groups and periods. The vertical columns in the periodic table is called groups and the horizontal rows are called periods.

A group contains elements with same number of valence electrons and similar physical and chemical properties. In a period from left to right the atomic number increases but the number of orbitals in which the electrons are filled will be the same.

Down a group the number of orbitals increases by one. Thus, each elements contains electrons in an increment of 8, 18, 18 and 32 down a group. Thus, from third period to fourth period the number of orbital increases to 4.

The number of electrons will be +8 from the previous element in the group in third period. Thus, below sodium (11) the first element in fourth period is potassium with 19 electrons.

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Answer: 0.377 moles of calcium chloride will be formed.

Explanation:

To calculate the moles :

[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]    

[tex]\text{Moles of} Ca(OH)_2=\frac{27.9g}{74g/mol}=0.377moles[/tex]

The balanced chemical reaction is:

[tex]Ca(OH)_2+2HCl\rightarrow CaCl_2+2H_2O[/tex]  

According to stoichiometry :  

As 1 mole of [tex]Ca(OH)_2[/tex] give = 1 mole of [tex]CaCl_2[/tex]

Thus 0.377 moles of [tex]Ca(OH)_2[/tex] give =[tex]\frac{1}{1}\times 0.377=0.377moles[/tex]  of [tex]CaCl_2[/tex]  

Thus 0.377 moles of calcium chloride will be formed upon the complete reaction of 27.9 grams of calcium hydroxide with excess hydrochloric acid

Answer:

90 mV

Explanation:

Faraday constant, F = 96487

Gas constant, R = 8.314

Number of mole of electron transferred, Z = 2

MgCl in solution A, = 0.1 mm

MgCl in solution A, = 100 mm

Using the relation :

E=(RT/ZF) In(Mg out/Mgin)

E = (8.314*298) / (2*96485) * In(100/0.1)

E = (2477.572 / 192970) * 6.9077552

E = 0.0128391 * 6.9077552

E = 0.0886897 V

E = 88.68 mV (approximately 90 mV)

Answer:

Density, d = 5.96 g/mL

Explanation:

Given that,

Mass, m = 105 g

Volume, V = 17.6 mL

We need to find the density of the substance. So,

[tex]d=\dfrac{m}{V}\\\\d=\dfrac{105\ g}{17.6\ mL}\\\\d=5.96\ g/mL[/tex]

So, the density of the substance is 5.96 g/mL.

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:

сфоткай отправь. я не магу зделать

According to the concept of Avogadro's number, there are 29.056×10²³ molecules in 77.2 g of methane.

Avogadro's number is defined as a proportionality factor which relates number of constituent particles with the amount of substance which is present in the sample.

It has a SI unit of reciprocal mole whose numeric value is expressed in reciprocal mole which is a dimensionless number and is called as Avogadro's constant.It relates the volume of a substance with it's average volume occupied by one of it's particles .

According to the definitions, Avogadro's number depend on determined value of mass of one atom of those elements.It bridges the gap between macroscopic and microscopic world by relating amount of substance with number of particles.

Number of atoms can be calculated using Avogadro's number as follows: mass/molar mass×Avogadro's number

In the given example, number of moles=77.2/16=4.825 moles

If 1 mole has 6.023×10²³ molecules , then 4.825 moles will have 4.825×6.023×10²³ /1=29.056×10²³ molecules .

Thus, there are 29.056×10²³ molecules in 77.2 g of methane.

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Answer:

[tex]k_2=2.46[/tex]

Explanation:

Hello!

In this case, according to the Arrhenius equation for variable temperature:

[tex]ln(\frac{k_2}{k_1} )=-\frac{Ea}{R}(\frac{1}{T_2} -\frac{1}{T_1} )[/tex]

Given the temperatures to be computed in kelvins and the activation energy, we obtain:

[tex]ln(\frac{k_2}{0.924} )=-\frac{89800J/mol}{8.314J/(mol*K)}(\frac{1}{306.45K} -\frac{1}{298.15K} )\\\\ln(\frac{k_2}{0.924} )=0.981\\\\k_2=0.924*exp(0.981)\\\\k_2=2.46[/tex]

Best regards!

Answer:

369 ml

Explanation:

Mass of Aluminium (Al) = 20 g

Molar concentration =  2.007M

Molar concentration = Number of moles / Volume

The relationship between mass and number of moles;

Number of moles = Mass / Molar mass

Number of moles = 20 / 27 = 0.741 mol

2.007  = 0.741  / Volume

Volume = 0.741 / 2.007 = 0.369 L

converting to millilitres by multiplying by 1000

Volume = 0.369 * 1000 = 369 ml

Answer:

any gas takes up 22.4L per mole so 2.4*22.4=53.76

Explanation:

In 2.4 moles at STP, 53.79 litres of N2 gas are present.

Moles are defined as the amount of substance of a system that contain the same number of entities as the number of atoms in 12g of carbon 12.

STP is defined as the standard temperature and pressure. At STP, as system has s temperature of zero degree centigrade or 273 Kelvin and the pressure is 1 atm.

PV= nRT

P= 1 atm

V= ?

n= 2.4 moles

R= 0.0821 L atm /K/mol

1 x V = 2.4 x 0.0821 x 273

V = 53.79 litres

Hence, 53.79 litres of N2 gas is present in 2.4 moles at STP.

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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:

44.84 ml

Explanation:

14.86

+

15.0

+

14.980

_______

44.84

Answer:

68.1% is percent yield of the reaction

Explanation:

The reaction of methane with oxygen is:

CH₄ + 2O₂ → CO₂ + 2H₂O

Where 2 moles of oxygen react per mole of CH₄

Percent yield is:

Actual yield (28.2g CO₂) / Theoretical yield * 100

To solve this question we need to find theoretical yield finding limiting reactant :

Moles CH₄:

15.1g CH₄ * (1mol / 16.04g) = 0.9414 moles

Moles O₂:

81.2g * (1mol / 32g) = 2.54 moles

For a complete reaction of 0.9414 moles of CH₄ are needed:

0.9414 moles CH₄ * (2 mol O₂ / 1mol CH₄) = 1.88 moles of O₂. As there are 2.54 moles, O₂ is in excess and CH₄ is limiting reactant

In theoretical yield, the moles of methane added = Moles of CO₂ produced. That is 0.9414 moles CO₂. In grams = Theoretical yield:

0.9414 moles CO₂ * (44.01g / mol) = 41.43g CO₂

Percent yield: 28.2g CO₂ / 41.43g CO₂ * 100=