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2 years ago

A chemist obtains a sample of

Chemistry

1 answer:

djverab [1.8K]2 years ago

7 0

The number of formula units of Na₂SO₄ present in the sample is 3.01×10²³ units

<h3>Avogadro's hypothesis </h3>

From Avogadro's hypothesis,

1 mole of Na₂SO₄ = 6.02×10²³ units

But

1 mole of Na₂SO₄ = (23×2) + 32 + (16×4) = 142 g

Thus,

142 g of Na₂SO₄ = 6.02×10²³ units

<h3>How to determine the units in 71 g of sample </h3>

142 g of Na₂SO₄ = 6.02×10²³ units

Therefore,

71 g of Na₂SO₄ = (71 × 6.02×10²³) / 142

71 g of Na₂SO₄ = 3.01×10²³ units

Thus, 3.01×10²³ units of Na₂SO₄ is present in the sample

Learn more about Avogadro's number:

brainly.com/question/26141731

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aleksklad [387]

<span>A. Helium </span>atomic number 2
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2 years ago

Kc = 3.07 x 10-4 at 24°C for 2NOBr(g) ↔ 2NO(g) + Br2(g). If the initial concentration of NOBr = 0.878 M, what is the equilibrium

pav-90 [236]

Answer:

The equilibrium concentration of NO is 0.02124 M.

Explanation:

Given that,

Initial concentration of NOBr = 0.878 M

$k_{c}=3.07\times10^{-4}$

Temperature = 24°C

We know that,

The balance equation is

$2NOBr\Rightarrow 2NO+Br_{2}$

Initial concentration is,

$0.878\Rightarrow 0+0$

Concentration is,

$-2x\Rightarrow 2x+x$

Equilibrium concentration

$0.878-2x\Rightarrow 2x+x$

We need to calculate the value of x

Using formula of concentration

$k_{c}=\dfrac{[NO][Br_{2}]}{[NOBr]^2}$

Put the value into the formula

$3.07\times10^{-4}=\dfrac{[2x][x]}{[0.878-2x]^2}$

$2x^2=3.07\times10^{-4}\times(0.878)^2+3.07\times10^{-4}\times4x^2-2\times2x\times0.878\times3\times10^{-4}$

$2x^2=0.0002367+0.001228x^2-0.0010536x$

$2x^2-0.001228x^2+0.0010536x-0.0002367=0$

$1.998772x^2+0.0010536x-0.0002367=0$

$x=0, 0.01062$

We need to calculate the equilibrium concentration of NO

Using formula of concentration of NO

$concentration\ of\ NO=2x$

Put the value of x

$concentration\ of\ NO=2\times0.01062$

$concentration\ of\ NO=0.02124$

Hence, The equilibrium concentration of NO is 0.02124 M.

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3 years ago

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Sever21 [200]

Answer:

It's called the shielding effect

Explanation:

It describes the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell. (I hope this helps)

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2 years ago

Which 2 resonance forms destablize the carbocation intermediate if bezonitrile undergoes chlronation at the ortho or para positi

Anna11 [10]

The question is incomplete, the complete question is shown in the image attached

Answer:

A and B

Explanation:

The electrophilic substitution of arenes yields a cation intermediate. The positive charge of the cation is delocalized over the entire ring.

The -CN group directs incoming electrophiles to the ortho/para position. The resonance structures for the chlorination of benzonitrile are shown in the question.

Recall that -CN is an electron withdrawing group. The resonance forms that destablize the carbocation intermediate are those in which the -CN group is directly attached to the carbon atom bearing the positive charge as in structures A and B.

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3 years ago

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Mazyrski [523]

<span>1. The two qualities used to describe winds are direction and speed.
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