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3 years ago

When Mendeleev started his work on organizing the elements, about how many had

Chemistry

1 answer:

Talja [164]3 years ago

8 0

Answer:

About 60.

Explanation:

Mendeleev knew of 63 elements. He wrote their properties on cards and arranged them in order of atomic mass.

That's how he discovered that the properties of elements are periodic functions of their atomic masses.

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HELP! PLEASE! ASAP! Manganese(III) fluoride, MnF3, can be prepared by the following reaction:

Crank

Answer:

14.336 g MnF₂

Explanation:

number of moles = mass / molecular weight

number of moles of MnI₂ = 55 / 309 = 0.178 moles

number of moles of F₂ = 55 / 38 = 1.447 moles

From the reaction and the number of moles calculated we deduce that the fluorine F₂ is a limiting reactant.

So:

if 13 moles of F₂ reacts to produce 2 moles of MnF₃

then 1.447 moles of F₂ reacts to produce X moles of MnF₃

X = (1.447 × 2) / 13 = 0.223 moles of MnF₃ (100% yield)

For 57.2% yield we have:

number of moles of MnF₃ = (57.2 / 100) × 0.223 = 0.128 moles

mass = number of moles × molecular weight

mass of MnF₃ = 0.128 × 112 = 14.336 g

3 0

3 years ago

Your body contains vast numbers of carbon atoms. How is it possible that some of these carbons may have been part of the body of

charle [14.2K]

Carbon is reused through the carbon cycle.

There is carbon in oil, which is made of ancient animals, and this carbon is discharged into the air during ignition.

Carbon is then taken in by plants as CO2, which we then eat.

<u>Explanation</u>:

Carbon is reused through the carbon cycle. There is carbon in oil, which is made of ancient animals, and this carbon is discharged into the air during ignition. Carbon is then taken in by plants as CO2, which we then eat.

Matter carries on as indicated by the guideline of conservation of matter: Under conventional conditions, any matter is neither made nor destroyed but instead is reused again and again. It tends to be changed or recombined, however, it doesn't vanish; everything heads off to someplace.

Carbon particles of my body presumably used to be a piece of the body of a prehistoric creature, as chemical components have been utilized and reused by living animals.

6 0

3 years ago

Electromagnetic waves consist of

sineoko [7]

Electromagnetic consists of both electrical and magnetic fields so D. :)

3 0

3 years ago

When 231. mg of a certain molecular compound X are dissolved in 65. g of benzene (CH), the freezing point of the solution is mea

Elan Coil [88]

Answer:

Molar mass X = 18.2 g/mol

Explanation:

Step 1: Data given

Mass of compound X = 231 mg = 0.231 grams

Mass of benzene = 65.0 grams

The freezing point of the solution is measured to be 4.5 °C.

Freezing point of pure benzene = 5.5 °C

The freezing point constant for benzene is 5.12 °C/m

Step 2: Calculate molality

ΔT = i*Kf*m

⇒ΔT = the freezing point depression = 5.5 °C - 4.5 °C = 1.0 °C

⇒i = the Van't hoff factor = 1

⇒Kf = the freezing point depression constant for benzene = 5.12 °C/m

⇒m = the molality = moles X / mass benzene

m = 1.0 / 5.12 °C/m

m = 0.1953 molal

Step 3: Calculate moles X

Moles X = molality * mass benzene

Moles X = 0.1953 molal * 0.065 kg

Moles X = 0.0127 moles

Step 4: Calculate molar mass X

Molar mass X = mass / moles

Molar mass X = 0.231 grams / 0.0127 moles

Molar mass X = 18.2 g/mol

5 0

3 years ago

melting, boiling, and bending are considered physical changes, but burning is a chemical change. explain why this is so.

Naya [18.7K]

<span>So, when you make something boiling or melting, its still the same substance. Water doesn't change into something else, just change its state of matter. When you burn something, one substance reacts with another. For example, when you burn carbon in oxygen, you get carbon dioxide. That's the difference.</span>

8 0

4 years ago