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3 years ago

Essentially, the oxygen we breath is

Chemistry

1 answer:

stepan [7]3 years ago

3 0

Answer:

Explanation:

Plants need carbon dioxide and let out oxygen

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Ok so I don't understand how to do this-

aleksandr82 [10.1K]

Answer:

Oh, you are supposed to look up the yearly temp, and yearly rain for a certain area. I did this before!

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3 years ago

Which of the following is not a clue that a chemical reaction has taken place? *

DaniilM [7]

Answer:

A pure solid is heated and turns into a pure liquid.

Explanation:

No colour change recorded, only change of state, hence this is a physical change - physical changes I.e. change of state and temperature are not chemical reactions.

7 0

3 years ago

Ba(NO3)2<br> What’s the atomic mass

Ahat [919]

Answer:

261.337 g/mol

Explanation:

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3 years ago

How many moles are in 7.2x10^15 atoms of Pb?

fiasKO [112]

<h3>Answer:</h3>

1.2 × 10⁻⁸ mol Pb

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

<u>Math</u>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right<u> </u>

<u>Chemistry</u>

<u>Atomic Structure</u>

Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

<u>Stoichiometry</u>

Using Dimensional Analysis

<h3>Explanation:</h3>

<u>Step 1: Define</u>

[Given] 7.2 × 10¹⁵ atoms Pb

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

Avogadro's Number

<u>Step 3: Convert</u>

[DA] Set up: $\displaystyle 7.2 \cdot 10^{15} \ atoms \ Pb(\frac{1 \ mol \ Pb}{6.022 \cdot 10^{23} \ atoms \ Pb})$
[DA] Multiply/Divide [Cancel out units]: $\displaystyle 1.19562 \cdot 10^{-8} \ mol \ Pb$

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 2 sig figs.</em>

1.19562 × 10⁻⁸ mol Pb ≈ 1.2 × 10⁻⁸ mol Pb

6 0

3 years ago

A 2.17 gm sample barium reacted completely with water what is the equation for the reaction how many milliliters of dry H2 evole

vaieri [72.5K]

Answer:

400 mL

Explanation:

Given data:

Mass of barium = 2.17 g

Pressure = 748 mmHg (748/760 = 0.98 atm)

Temperature = 21 °C ( 273+ 21 = 294k)

Milliliters of H₂ evolved = ?

Solution:

chemical equation:

Ba + 2H₂O → Ba(OH)₂ + H₂

Number of moles of barium:

Number of moles = mass/ molar mass

Number of moles = 2.17 g / 137.327 g/mol

Number of moles = 0.016 mol

Now we will compare the moles of barium with H₂.

Ba : H₂

1 : 1

0.016 : 0.016

Milliliters of H₂:

PV = nRT

V = nRT/P

V = 0.016 mol × 0.0821 atm. mol⁻¹.k⁻¹.L×294 k/0.98 atm

V = 0.39 atm. L/0.98 atm

V = 0.4 L

L to mL

0.4 × 1000 = 400 mL

8 0

3 years ago