I believe its the remains of plants and animals millions of years old.
Answer: d)endothermic with a positive entropy change
Explanation:
Endothermic reactions are those in which heat is absorbed by the system and exothermic reactions are those in which heat is released by the system.
Entropy is the measure of randomness or disorder of a system. If a system moves from an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.
As temperature of water decreases on dissolution of , it means heat has been absorbed by during dissolution and that heat is taken from water. Thus process is endothermic. As dissolution will lead in the formation of ions and , randomness will increase and thus there is a positive entropy change.
Answer:
15.3 g
Explanation:
- Fe₂O₃ (s) + 2Al (s) → 3Fe (l) + Al₂O₃ (s)
First we convert 8.0 grams of aluminum into moles, using its molar mass:
- 8.0 g Al ÷ 27 g/mol = 0.30 mol Al
Then we <u>convert 0.30 moles of aluminum into moles of aluminum oxide</u>, using the<em> stoichiometric coefficients</em>:
- 0.30 mol Al * = 0.15 mol Al₂O₃
Finally we convert 0.15 moles of Al₂O₃ into grams, using its molar mass:
- 0.15 mol Al₂O₃ * 102 g/mol = 15.3 g Al₂O₃
Answer:
6.25 mL
Explanation:
1.25% of 500 mL is ...
0.0125×(500 mL) = 6.25 mL
Since 1.25% of the 500 mL of solution is bleach, that's how much you need. That amount is 6.25 mL.
Answer:
-152.92°C
Explanation:
Initial volume = 0.750 mL
Initial temperature = -32.7 °C (-32.7 + 273.15 K = 240.45 k)
Final temperature = ?
Final volume = 0.750 mL / 2= 0.375 mL
Solution:
The given problem will be solve through the Charles Law.
Mathematical expression:
V₁/T₁ = V₂/T₂
V₁ = Initial volume
T₁ = Initial temperature
V₂ = Final volume
T₂ = Final temperature
Now we will put the values in formula.
V₁/T₁ = V₂/T₂
T₂ = T₁V₂ / V₁
T₂ = 240.45 k × 0.375 mL / 0.750 mL
T₂ = 90.17 mL.K / 0.750 mL
T₂ = 120.23 K
Temperature in celsius:
120.23 K - 273.15 = -152.92°C