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3 years ago

Which of the following is always a reactant in a combustion reaction?

Chemistry

2 answers:

Margaret [11]3 years ago

6 0

I believe it’s oxygen

Marina86 [1]3 years ago

5 0

Answer:

Oxygen

Explanation:

Any Hydrocarbon + Oxygen ----> Carbon Dioxide + H2O (Water vapour, gas, water)

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Element definition in chemistry

pav-90 [236]

An element is a substance made entirely from one type of atom. For example, the element hydrogen is made from atoms containing a single proton and a single electron.

5 0

3 years ago

How many grams of molybdenum(Mo) are in 2.68E24 atoms of Mo?

loris [4]

<h3>Answer:</h3>

427 g Mo

<h3>General Formulas and Concepts:</h3>

<u>Chemistry</u>

<u>Atomic Structure</u>

Reading a Periodic Table
Using Dimensional Analysis
Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

<h3>Explanation:</h3>

<u>Step 1: Define</u>

2.68E24 atoms Mo or 2.68 × 10²⁴ atoms Mo

<u>Step 2: Identify Conversions</u>

Avogadro's Number

Molar Mass of Mo - 95.94 g/mol

<u>Step 3: Convert</u>

<u /> $2.68 \cdot 10^{24} \ atoms \ Mo(\frac{1 \ mol \ Mo}{6.022 \cdot 10^{23} \ atoms \ Mo} )(\frac{95.94 \ g \ Mo}{1 \ mol \ Mo} )$ = 426.966 g Mo

<u>Step 4: Check</u>

<em>We are given 3 sig figs. Follow sig fig rules and round.</em>

426.966 g Mo ≈ 427 g Mo

3 0

3 years ago

Calculate the cell potential for the following reaction as written at 25.00 °C, given that [Cr2 ] = 0.892 M and [Fe2 ] = 0.0150

Effectus [21]

<u>Given:</u>

Concentration of Cr2+ = 0.892 M

Concentration of Fe2+ = 0.0150 M

<u>To determine:</u>

The cell potential, Ecell

<u>Explanation:</u>

The half cell reactions for the given cell are:

Anode: Oxidation

Cr(s) ↔ Cr2+(aq) + 2e⁻ E⁰ = -0.91 V

Cathode: Reduction

Fe2+ (aq) + 2e⁻ ↔ Fe (s) E⁰ = -0.44 V

------------------------------------------

Net reaction: Cr(s) + Fe2+(aq) ↔ Cr2+(aq) + Fe(s)

E°cell = E°cathode - E°anode = -0.44 - (-0.91) = 0.47 V

The cell potential can be deduced from the Nernst equation as follows:

Ecell = E°cell - (0.0591/n)log[Cr2+]/[Fe2+]

Here, n = number of electrons = 2

Ecell = 0.47 - 0.0591/2 * log[0.892]/[0.0150] = 0.418 V

Ans: The cell potential is 0.418 V

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3 years ago

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Which idea was supported by Aristarchus, Copernicus, and Galileo?

n200080 [17]

Answer: The planets revolve around the sun.

Explanation: Its common knowledge...

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3 years ago

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What new scientific evidence led to changes in Dalton's atomic theory?

Masja [62]

Drawbacks of Dalton's Atomic Theory. The indivisibility of an atom was proved wrong: an atom can be further subdivided into protons, neutrons and electrons. However an atom is the smallest particle that takes part in chemical reactions. According to Dalton, the atoms of same element are similar in all respects.

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3 years ago