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horrorfan [7]
3 years ago
6

Determine whether each described process is endothermic or exothermic.

Chemistry
1 answer:
FromTheMoon [43]3 years ago
7 0

Answer:

Ice melts into liquid water- endothermic

A process with a calculated positive q - endothermic

Wood burns in a fireplace - exothermic

A process with a calculated negative q - exothermic

Acid and base are mixed, making test tube feel hot - exothermic

Solid dissolves into solution, making ice pack feel cold - endothermic

Explanation:

An endothermic process is one in which heat is absorbed from the surroundings. The absorption of heat means that heat is removed from the surroundings hence the surroundings feel cool. When heat is absorbed, q is positive.

An exothermic process is one in which heat is released to the surroundings. The evolution of heat means that heat is released into the surroundings hence the surroundings feel hot . When heat is evolved, q is negative.

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Alloy i believe if so 
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4 years ago
How does a buffer resist change in pH upon addition of a strong acid? The strong acid reacts with the strong base in the buffer
MrRa [10]

Answer:

The strong acid reacts with the weak base in the buffer to form a weak acid, which produces few H+ ions in solution and therefore only a little change in pH.

Explanation:

When a strong acid is added to the buffer, the acid dissociates and furnish hydrogen ions which combine with the conjugate of the weak acid, forming weak acid. The weak acid dissociates to only some extent and can furnish only some protons and there is no significant change in the pH.

Hence, option B is correct.

4 0
3 years ago
Calculate the standard enthalpy change for the reaction at 25 ∘ C. Standard enthalpy of formation values can be found in this li
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Answer:

-179.06 kJ

Explanation:

Let's consider the following balanced reaction.

HCl(g) + NaOH(s) ⟶ NaCl(s) + H₂O(l)

We can calculate the standard enthalpy change for the reaction (ΔH°r) using the following expression.

ΔH°r = 1 mol × ΔH°f(NaCl(s)) + 1 mol × ΔH°f(H₂O(l)) - 1 mol × ΔH°f(HCl(g)) - 1 mol × ΔH°f(NaOH(s))

ΔH°r = 1 mol × (-411.15 kJ/mol) + 1 mol × (-285.83 kJ/mol) - 1 mol × (-92.31 kJ/mol) - 1 mol × (-425.61 kJ/mol)

ΔH°r = -179.06 kJ

7 0
3 years ago
All methods of chromatography operate on the same basic principle that Select one: a. one component of the mixture will chemical
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Answer:C

Explanation:

Chromatography separates compounds by taking advantage of their polarity. The stationary phase is generally very polar. The mobile phase can be pure hexane or various ratios of hexane with a polar eluent added. The more polar the compound, the more it interacts with the stationary phase and won’t move very far up the plate compared to the non-polar or less polar compounds that interact more with the non-polar hexane.

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3 years ago
A beaker containing 80 grams of lead(ii) nitrate, pb(no3)2, in 100 grams of water has a temperature of 30 ºc. approximately how
sukhopar [10]

Answer:

14 g.

Explanation:

  • From the figure attached:

<em>the solubility of lead(II) nitrate, Pb(NO₃)₂, in 100 grams of water has a temperature of 30ºC is </em><em>(66 g).</em>

When beaker containing 80 grams of lead(II) nitrate, Pb(NO₃)₂, in 100 grams of water has a temperature of 30ºC.

<em>∴ The grams of the salt are undissolved, on the bottom of the beaker are </em><em>(14 g).</em>

4 0
3 years ago
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