Answer: the color of the solid will change
Explanation:
A chemical reaction is defined as the reaction in which a change in chemical composition takes place. A new substance is formed in these reactions.
Example: Oxidation of iron to ferric oxide is a chemical change.
Here iron which is grey in color changes first to green and then turns brownish red.
Characteristics of a chemical reaction:
1. change in color
2. heat is gained or lost
3. evolution of gas
4. formation of precipitate
False
Answer:
Option B. Add 1.46 g of NaCl to 250 mL of H₂O
Explanation:
Analyse the data given: 250 mL and 0.10 M
The molar concentration and the volume of solution can indicate the moles of solute that were used.
Let's convert the volume from mL to L → 250 mL . 1 L /1000mL =0.250L
M . volume = moles → 0.10 mol/L . 0.250L = 0.025 moles
If we convert the moles to mass, we'll know the mass of solute:
0.025 mol . 58.4 g/mol = 1.46 g
Answer:
We have to solve 1.46 grams of NaCl in 250 mL H2O (option B)
Explanation:
Step 1: Data given
Volume = 250 mL = 0.250 L
Molarity NaCl solution = 0.10 M
Molar mass of NaCl = 58.4 g/mol
Step 2: Calculate moles NaCl
Moles NaCl = molarity * volume
Moles NaCl = 0.10 M * 0.250 L
Moles NaCl = 0.025 moles
Step 3: Calculate mass NaCl
Mass NaCl = moles NaCl * molar mass NaCl
Mass NaCl = 0.025 moles * 58.4 g/mol
Mass NaCl = 1.46 grams
We have to solve 1.46 grams of NaCl in 250 mL H2O (option B)
TrueFalse
2NO2 (g) --> N2 (g) + 2O2 (g)
C5H12 (g) + 8O2 (g) --> 5CO2 (g) + 6H2O (g)
2NaClO3 (s) --> 2NaCl (s) + 3O2 (g)
2Na (s) + Cl2 (g) --> 2NaCl (s)
CH3OH (l) --> CH3OH (g)
Answer:
(i) ΔS° < 0 or negative
(ii) ΔS° > 0 or positive
(iii) ΔS° > 0 or positive
(iv) ΔS° > 0 or positive
(v) ΔS° < 0 or negative
(vi) ΔS° > 0 or positive
Explanation:
Entropy is a state function and extensive property of the system.
It's the measurement of degree of randomness..
Entropy of the system decreases as follows
Gas > Liquid > Amorphous solid > Crystalline solid.
In case for chemical reaction
(i) Ba²⁺ (aq) + SO₄²⁻ (aq) --> BaSO₄ (s)
Total entropy change ΔS° < 0 or negative
During this reaction aqueous i.e liquid phase converted into solid phase.
So randomness decreases and hence entropy also decreases.
(ii) 2 NO₂ (g) --> N₂ (g) + 2 O₂ (g) ΔS° > 0 or positive
Since no. of gaseous moles increases from reactants to products.
(iii) C₅H₁₂ (g) + 8 O₂ (g) --> 5 CO₂ (g) + 6 H₂O (g) ΔS° > 0 or positive
Since no. of gaseous moles increases from reactants to products.
(iv) 2 NaClO₃ (s) --> 2 NaCl (s) + 3 O₂ (g) ΔS° > 0 or positive
Since no. of gaseous moles increases from reactants to products.
(v) 2 Na (s) + Cl₂ (g) --> 2 NaCl (s) ΔS° < 0 or negative
Since no. of gaseous moles decreases from left to right so entropy also decreases.
(vi) CH₃OH (l) --> CH₃OH (g) ΔS° > 0 or positive
Because during this phase transition Liquid to gaseous randomness increases and hence entropy also increases.