Burning, cooking
Explanation:
Chemical changes that happens in school are:
Cooking of meals
Burning of wastes
Chemical reactions in laboratories
Rusting of iron used in construction
- A chemical change is a change that produces new kinds of substances.
- These changes are usually accompanied by energy and mass changes.
- Most of such changes are not reversible.
Chemical changes are driven by change in chemical properties of matter.
In a school, iron components might begin to rust. This is a chemical change.
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<h3>
Answer:</h3>
0.50 mol SiO₂
<h3>
General Formulas and Concepts:</h3>
<u>Math</u>
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
<u>Chemistry</u>
<u>Atomic Structure</u>
- Reading a Periodic Table
- Using Dimensional Analysis
<h3>
Explanation:</h3>
<u>Step 1: Define</u>
30 g SiO₂ (sand)
<u>Step 2: Identify Conversions</u>
Molar Mass of Si - 28.09 g/mol
Molar Mass of O - 16.00 g/mol
Molar Mass of SiO₂ - 28.09 + 2(16.00) = 60.09 g/mol
<u>Step 3: Convert</u>
- Set up:

- Multiply/Divide:

<u>Step 4: Check</u>
<em>Follow sig figs and round. We are given 2 sig figs.</em>
0.499251 mol SiO₂ ≈ 0.50 mol SiO₂
159.3 g
mol= mass (g)/ molecular weight (g/mol)
Answer:
1.3 × 10³ cm³
Explanation:
The gas occupies a volume of V₁ = 310 cm³ under standard temperature and pressure (STP), that is, T₁ = 273.15 K and P₁ = 1.0 atm. In order to find the volume V₂ under different conditions we can use the combined gas law formula.

Answer:
1.45 x 10²³ particles
Explanation:
Given parameters:
Number of moles of carbon = 0.24moles
Unknown:
Number of particles = ?
Solution:
A mole of a substance contains the Avogadro's number of particles.
The Avogadro's number of particles is 6.02 x 10²³
So;
0.24 moles of carbon will contain 0.24 x 6.02 x 10²³ = 1.45 x 10²³ particles