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kow [346]
3 years ago
6

What sample size (grams) of Na3PO4 (FW 164.00) known to be 50.00% pure should be used to consume exactly 40.00 mL of 0.1000 M HC

l to reach the 2nd end point
Chemistry
1 answer:
Mkey [24]3 years ago
3 0

Answer:

0.109 g.

Explanation:

Equation of the reaction:

Na3PO4 + 3HCl --> 3NaCl + H3PO4

Number of moles of HCl = molar concentration × volume

= 0.1 × 0.04

= 0.004 mol.

By stoichiometry, 1 mole of Na3PO4 neutralises 3 moles of HCl. Therefore, number of moles of Na3PO4 = 0.004/3

= 0.0013 mol

Mass of Na3PO4 = molar mass × number of moles

= 0.0013 × 164

= 0.219 g

Since 50% of Na3PO4 was present in the sample. Let 100 g be the total mass of the substance

= 0.219 × 50 g/100 g

= 0.109 g.

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3 years ago
A 2.04 g lead weight, initially at 10.8 oC, is submerged in 7.62 g of water at 52.3 oC in an insulated container. clear = 0.128
alisha [4.7K]

Answer: The final temperature of both the weight and the water at thermal equilibrium is 50.26^{o}C.

Explanation:

The given data is as follows.

mass = 7.62 g,           T_{2} = 10.8^{o}C

Let us assume that T be the final temperature. Therefore, heat lost by water is calculated as follows.

       q = mC \times \Delta T    

          = 7.62 g \times 4.184 J/^{o}C \times (52.3 - T)

Now, heat gained by lead will be calculated as follows.

       q = mC \times \text{Temperature change of lead}  

           = 2.04 \times 0.128 \times (T - 11.0)

According to the given situation,

     Heat lost = Heat gained

7.62 g \times 4.184 J/^{o}C \times (52.3 - T) = 2.04 \times 0.128 \times (T - 11.0)

        T = 50.26^{o}C

Thus, we can conclude that the final temperature of both the weight and the water at thermal equilibrium is 50.26^{o}C.

7 0
3 years ago
In a solution with a pH of 3.0, the color of
Alinara [238K]

Answer:

A) litmus is red

Explanation:

To answer this question, it can be helpful to have the color charts. Litmus, phenolphthalein and methyl orange are ways to test the pH of a substance.

<u>Litmus paper</u>

Litmus can tell you if a substance is an acid or a base. You need to put the substance on both red litmus and blue litmus paper.

pH < 7: both papers are red. 3.0 is less than 7.

pH = 7: none of them change color

pH > 7: both papers are blue

<u>Phenolphthalein</u>

When this indicator is added to a substance, the result is either colorless or pink.

0 < pH ≤ 7: colorless. The color is not red or blue for pH 3.0.

pH > 7: pink

<u>Methyl orange</u>

0 < pH < 4: red. The color is not yellow if the pH is 3.0.

4 ≤ pH < 5: orange

pH ≥ 5: yellow

5 0
3 years ago
When nad becomes nadh, it is being? oxidized and releasing chemical energy. reduced and gaining chemical energy. oxidized and ga
3241004551 [841]

When NAD becomes NADH, it is being reduced and gaining chemical energy.

Nicotinamide adenine dinucleotide (NAD), a coenzyme, can exist in two forms, NAD⁺ (oxidized) and NADH (reduced form).

Electrons and protons released in catabolism reactions are attached to NAD⁺. The conversion of NAD⁺ to NADH is important reaction for production of ATP during the cellular respiration.

Reduction is lowering oxidation number because element, ion or compound gain electrons.

Chemical equation for reaction of reduction of NAD⁺ (see picture below):

NAD⁺ + 2e⁻ + H⁺ → NADH

Nicotinamide adenine dinucleotide (NAD) is made of two nucleosides joined by pyrophosphate.

More about reduction :brainly.com/question/25334331

#SPJ4

8 0
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