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wolverine [178]
3 years ago
13

A mixture contains NaHCO3 together with unreactive components. A 1.54 g sample of the mixture reacts with HA to produce 0.561 g

of CO2. What is the percent by mass of NaHCO3 in the original mixture
Chemistry
1 answer:
Marianna [84]3 years ago
8 0

Answer:

69.55 (w/w) %

Explanation:

When NaHCO3 reacts with an acid HA, the reaction that occurs is:

NaHCO3 + HA → H2O + NaA + CO2

<em>Where 1 mole of NaHCO3 produce 1 mole of CO2</em>

<em />

Thus, we need to convert the mass of CO2 to moles using its molar mass (44g/mol). Then, based on the chemical equation, moles of CO2 produced are equal to moles of NaHCO3 in the mixture. With its molar mass -84g/mol- we can find the mass of NaHCO3 and mass percent:

<em>Moles CO2:</em>

0.561g * (1mol / 44g) = 0.01275 moles CO2 = Moles NaHCO3.

<em>Mass NaHCO3:</em>

0.01275 moles * (84g/mol) = 1.071g NaHCO3

<em>Mass percent:</em>

1.071g NaHCO3 / 1.54g sample * 100

<h3>69.55 (w/w) %</h3>

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In the reaction 2Mg (s) + O2 (g) + 2H2O (l) → 2Mg2+ (aq) + 4OH– (aq), which substance is reduced?
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F. <em>None of the above </em>

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6 0
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A radioactive element reduces to 5.00% of its initial mass in
Stolb23 [73]

The half-life in months of a radioactive element that reduce to 5.00% of its initial mass in 500.0 years is approximately 1389 months

To solve this question, we'll begin by calculating the number of half-lives that has elapsed. This can be obtained as follow:

Amount remaining (N) = 5%

Original amount (N₀) = 100%

<h3>Number of half-lives (n) =?</h3>

N₀ × 2ⁿ = N  

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2ⁿ = 100/5

2ⁿ = 20

Take the log of both side

Log 2ⁿ = log 20

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Divide both side by log 2

n = log 20 / log 2

<h3>n = 4.32</h3>

Thus, 4.32 half-lives gas elapsed.

Finally, we shall determine the half-life of the element. This can be obtained as follow.

Number of half-lives (n) = 4.32

Time (t) = 500 years

<h3>Half-life (t½) =? </h3>

t½ = t / n

t½ = 500 / 4.32

t½ = 115.74 years

Multiply by 12 to express in months

t½ = 115.74 × 12

<h3>t½ ≈ 1389 months </h3>

Therefore, the half-life of the radioactive element in months is approximately 1389 months

Learn more: brainly.com/question/24868345

8 0
2 years ago
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