Answer:
Chemical changes cause a substance to change into an entire substance with a new chemical formula. Chemical changes are also known as chemical reactions. The “ingredients” of a reaction are called reactants, and the results are called products.
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Answer:
H₃PO₄ → 3H⁺ + PO₄³⁻
CaSO₄ → Ca²⁺ + SO₄²⁻
b. CaCl₂
Explanation:
When H₃PO₄ is dissolved in water, there are produced the H⁺ and PO₄³⁻ ions. The equation is:
H₃PO₄ → 3H⁺ + PO₄³⁻
In the same way, CaSO₄ is dissolved in:
CaSO₄ → Ca²⁺ + SO₄²⁻
b. Now, in a reaction of an acid (HCl) and a base (Ca(OH)₂), water, H₂O and a salt are produced:
2 HCl + Ca(OH)₂ → 2H₂O + Salt
The ions that are not present in the reaction are Cl⁻ and Ca²⁺, the salt is CaCl₂ and the balanced reaction is:
2 HCl + Ca(OH)₂ → 2H₂O + CaCl₂
Answer is: line be long 3,011·10¹³ kilometers.
diametar of virus = 5·10⁻⁶ cm ÷ 100000 = 5·10⁻¹¹ km.
line lenght = 5·10⁻¹¹ km · 6,023·10²³.
line lenght = 3,011·10¹³ km.
Avogadro number = 6,023·10²³.
1 cm = 10⁻² m = 10⁻⁵ km.
Answer:
- The molarity of the student's sodium hydroxide solution is 0.0219 M
Explanation:
<u>1) Chemical reaction.</u>
a) Kind of reaction: neutralization
b) General form: acid + base → salt + water
c) Word equation:
- sodium hydroxide + oxalic acid → sodium oxalate + water
d) Chemical equation:
- NaOH + H₂C₂O₄ → Na₂C₂O₄ + H₂O
b) Balanced chemical equation:
- 2NaOH + H₂C₂O₄ → Na₂C₂O₄ + 2H₂O
<u>2) Mole ratio</u>
- 2mol Na OH : 1 mol H₂C₂O₄ :1 mol Na₂C₂O₄ : 2 mol H₂O
<u>3) Starting amount of oxalic acid</u>
- mass = 28 mg = 0.028 g
- molar mass = 90.03 g/mol
- Convert mass in grams to number of moles, n:
n = mass in grams / molar mass = 0.028 g / 90.03 g/mol = 0.000311 mol
<u>4) Titration</u>
- Volume of base: 28.4 mL = 0.0248 liter
- Concentration of base: x (unknwon)
- Number of moles of acid: 2.52 mol (calculated above)
- Proportion using the theoretical mole ratio (2mol Na OH : 1 mol H₂C₂O₄)

That means that there are 0.000622 moles of NaOH (solute)
<u>5) Molarity of NaOH solution</u>
- M = n / V (liter) = 0.000622 mol / 0.0284 liter = 0.0219 M
That is the correct number using <em>three signficant figures</em>, such as the starting data are reported.
<span>Estradiol is a type of steroid produced by the ovaries and it is strong that could cause gynecological problems and cancer.</span>