Answer:
11.31g NaClO₂
Explanation:
<em> Is given 250mL of a 1.60M chlorous acid HClO2 solution. Ka is 1.110x10⁻². What mass of NaClO₂ should the student dissolve in the HClO2 solution to turn it into a buffer with pH =1.45? </em>
It is possible to answer this question using Henderson-Hasselbalch equation:
pH = pKa + log₁₀ [A⁻] / [HA]
<em>Where pKa is -log Ka = 1.9547; [A⁻] is the concentration of the conjugate base (NaClO₂), [HA] the concentration of the weak acid</em>
You can change the concentration of the substance if you write the moles of the substances:
[Moles HClO₂] = 250mL = 0.25L×(1.60mol /L) = <em>0.40 moles HClO₂</em>
Replacing in H-H expression, as the pH you want is 1.45:
1.45 = 1.9547 + log₁₀ [Moles NaClO₂] / [0.40 moles HClO₂]
-0.5047 = log₁₀ [Moles NaClO₂] / [0.40 moles HClO₂]
<em>0.3128 = </em>[Moles NaClO₂] / [0.40 moles HClO₂]
0.1251 = Moles NaClO₂
As molar mass of NaClO₂ is 90.44g/mol, mass of 0.1251 moles of NaClO₂ is:
0.1251 moles NaClO₂ ₓ (90.44g / mol) =
<h3>11.31g NaClO₂</h3>
A chemical reaction that has a positive g is best described as endergonic.
Which device is designed to produce mechanical energy?
Well, mechanical energy is the sum of potential and kinetic energy. Kinetic energy is a unit of energy in which is the reason why an object does movement, while potential energy is another unit of energy in which is the reason why an object doesn't move, or stops. While you can stop a fan or a lamp, it isn't automatic. It's manually. So the answer is (4) an oven because mechanical energy happens automatically, not manually, or for a greater reason.
Answer:
Option B. A
Explanation:
From the question given above, the following data were obtained:
C(s) + 2H₂ (g) —> CH₄ (g). ΔH = –74.9 kJ
From the reaction above, we can see that the enthalpy change (ΔH) is negative (i.e –74.9 KJ) which implies that the heat content of the reactants is greater than the heat content of the products. Thus, the reaction is exothermic reaction.
For an exothermic reaction, the energy profile diagram is drawn in such a way that the heat content of reactants is higher than the heat content of products because the enthalpy change
(ΔH) is always negative.
Thus, diagram A (i.e option B) gives the correct answer to the question.
Answer:
Ingredient lists and nutritional facts
Explanation:
The packaged food, a consumer purchases has all its details written on the food package which is also verified by a trusted government institution.
The list tells each ingredient in food product by the food's common or usual name in the descending order by the weight.
- <u>Nutrition Facts Label
</u>
FDA requires this label on most of the packaged foods and the beverages. At top of Nutrition Facts label, there is written total number of the servings in container and serving size of food or drink. Serving size on label is based on amount of the food which people eat typically at one time. Rest of nutrition information on label is based usually on one serving of food or beverage.
