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Otrada [13]
3 years ago
8

How to calculate the mass of solid sodium hydroxide needed to prepare 200 ml of a 0.040m solution. if one pellet of sodium hydro

xide weighs 0.170g, how many pellets should be dissolved?
Chemistry
1 answer:
lbvjy [14]3 years ago
4 0
<span>0.496 g of NaOH required 3 pellets. First, determine the molar mass of NaOH. Atomic weight sodium = 22.989769 Atomic weight hydrogen = 22.989769 Atomic weight oxygen = 15.999 Molar mass NaOH = 22.989769 + 22.989769 + 15.999 = 61.978538 g/mol Now determine how many moles of NaOH we need. Multiply desired volume by desired molarity. So 0.200 l * 0.040 mol/l= 0.008 mol To get the mass, then multiply by the molar mass, so 0.008 mol * 61.978538 g/mol = 0.495828304 g Since we have the NaOH in pellet form, divide the desired mass by the mass of each pellet. So 0.495828304 g / 0.170 g/pellet = 2.916637082 pellets You'll need 3 pellets. To get closer to the desired molarity, I would recommend increasing the amount of solution being prepared if you can accurately measure the larger volume.</span>
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Metric prefix name for 1/100 ?
babymother [125]
The metric prefix name for 1/100 is centimeters.
5 0
3 years ago
Question 3) A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in LiF. Calculate the pH of the solution after the addition of
Masja [62]

The pH of the solution after adding 0.150 moles of solid LiF is 3.84

<u>Explanation:</u>

We have the chemical equation,

HF (aq)+NaOH(aq)->NaF(aq)+H2O

To find how many moles have been used in this

c= n/V=> n= c.V

nHF=0.250 M⋅1.5 L=0.375 moles HF

Simillarly

nF=0.250 M⋅1.5 L=0.375 moles F

nHF=0.375 moles - 0.250 moles=0.125 moles

nF=0.375 moles+0.250 moles=0.625 moles

[HF]=0.125 moles/1.5 L=0.0834 M

[F−]=0.625 moles/1.5 L=0.4167 M

To determine the problem using the Henderson - Hasselbalch equation

pH=pKa+log ([conjugate base/[weak acid])

Find the value of Ka

pKa=−log(Ka)

pH=−log(Ka) +log([F−]/[HF]

pH= -log(3.5 x 10 ^4)+log(0.4167 M/0.0834 M)

pH=-log(3.5 x 10 ^4)+log(4.996)

pH= -4.54+0.698

pH=-(-3.84)

pH=3.84

The pH of the solution after adding 0.150 moles of solid LiF is 3.84

5 0
3 years ago
Tính axit giảm dần của các chất C6H5 OH (1) ,p – CH3 OC6H4 OH (2), p-NO2C6H4OH (3) pCH3COC6H4OH (4), p-CH3C6H4 OH (5) là:
nadya68 [22]

Answer:

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Explanation:

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3 0
2 years ago
HRISTINA HERRERA: Attempt 1
Lunna [17]

Answer:

7.5 g of hydrogen gas reacts with 50.0 g oxygen gas to form 57.5 g of water.

Explanation:

Here we have the check if the mass of the reactants is equal to the mass of the products.

Reactants

7.5+50=57.5\ \text{g}

Products

57.5\ \text{g}

The data is consistent with the law of conservation of matter.

Reactants

50+243=293\ \text{g}

Products

206+97=303\ \text{g}

The data is not consistent with the law of conservation of matter.

Reactant

17.7+34.7=52.4\ \text{g}

Products

62.4\ \text{g}

The data is not consistent with the law of conservation of matter.

Only the first data is consistent with the law of conservation of matter.

8 0
3 years ago
Gas A effuses 0.68 times as fast as Gas B. If the molar mass of Gas B is 17 g, what is the mass of Gas A?
BartSMP [9]
The mass of gas A is 11.56. i got this answer by 0.68 multiplied by 17.  because in this problem the key word is times.
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3 years ago
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