Answer:
Heat flows from the block at high temperature to the one with lower temperature
Explanation:
The direction of heat flow is from a body at higher temperature to one with a lower temperature.
- Temperature gradient determines the way and manner in which heat is dissipated.
- As a system tend to increase entropy, it ensures that heat moves from hotter body to a colder body.
- Heat movement here is by conduction as the body touches.
- When both bodies reaches the same temperature, thermal equilibrium is established.
When sodium carbonate is dissolved in water, the equation is 
.
When carbon dioxide is placed in water, aqueous carbon dioxide is formed: 
<h3>Dissolution of compounds in water</h3>
Some compounds are water-soluble, some are just partially soluble, while others are insoluble in water. Some soluble or partially soluble substances dissociate in water into their component ions. These substances are said to be ionic.
Sodium carbonate, like every other sodium salt, is soluble in water. It dissolves in water to form an aqueous solution of sodium carbonate.
While in solution, sodium carbonate dissociates into its component ions according to the following equation:
Carbon dioxide, on the other hand, does not dissociate in water. Instead, it dissolves in water where most of it remains as aqueous carbon dioxide in equilibrium with a small amount of hydronium ion and hydrogen carbonate ion.
Since the hydronium and hydrogen carbonate ions formed are so minute, the equation of the reaction can be written as:
More on the dissolution of substances can be found here: brainly.com/question/28580758
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Answer:
ΔpH = 0.20
Explanation:
The buffer of HCO₃⁻ + CO₃²⁻ has a pka of 10.2
HCO₃⁻ ⇄ H⁺ + CO₃²⁻
There are 0.479moles of NaHCO₃ and 0.342moles of Na₂CO₃.
Using Henderson-Hasselbalch formula:
pH = pka + log [Base] / [Acid]
pH = 10.2 + log 0.342mol / 0.479mol
<em>pH = 10.05</em>
NaOH reacts with HCO₃⁻ producing CO₃²⁻, thus:
NaOH + HCO₃⁻ → CO₃²⁻ + H₂O + Na⁺
0.091 moles of NaOH produce the same moles of CO₃²⁻ and consume HCO₃⁻. Moles of these species are:
CO₃²⁻: 0.342mol + 0.091mol: 0.433mol
HCO₃⁻: 0.479mol - 0.091 mol: 0.388mol
Using Henderson-Hasselbalch formula:
pH = pka + log [Base] / [Acid]
pH = 10.2 + log 0.433mol / 0.388mol
pH = 10.25
That means change of pH, ΔpH is:
ΔpH = 10.25 - 10.05 = <em>0.20</em>
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I hope it helps!
The student's test average is : 0.92
Total score obtained = 369
Number of tests = 4
Since Each test is exactly 100 points ;
The total score obtainable is (100 × 4) = 400
Average = score obtained / total score obtainable
Average = 369 / 400
Average = 0.9225
Average = 0.92
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