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Katarina [22]
3 years ago
11

What is different about most of the elements of the 7th period?

Chemistry
2 answers:
11Alexandr11 [23.1K]3 years ago
3 0

Answer:

All elements of period 7 are radioactive. This period contains the actinides, which includes plutonium, the naturally occurring element with the heaviest nucleus; subsequent elements must be created artificially.

Explanation:

hope u understand :)

murzikaleks [220]3 years ago
3 0

Answer:

All elements of period 7 are radioactive. This period contains the actinides, which includes plutonium, the naturally occurring element with the heaviest nucleus; subsequent elements must be created artificially.

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An impure sample of table salt that weighed 0.8421 g, when dissolved in water and treated with excess AgNO3, formed 2.044 g of A
Lilit [14]

Answer:

99.24%.

Explanation:

  • NaCl reacted with AgNO₃ as in the balanced equation:

<em>NaCl + AgNO₃ → AgCl(↓) + NaNO₃,</em>

1.0 mol of NaCl reacts with 1.0 mol of AgNO₃ to produce 1.0 mol of AgCl and 1.0 mol of NaNO₃.

  • We need to calculate the no. of moles of AgCl produced:

no. of moles of AgCl = mass/molar mass = (2.044 g)/(143.32 g/mol) = 0.0143 mol.

  • Now, we can calculate the no. of moles of NaCl that can precipitated as AgCl (0.0143 mol), these moles represents the no. of moles of pure NaCl in the sample:

<em>using cross multiplication:</em>

1.0 mol of NaCl produce → 1.0 mol of AgCl, from the stichiometry.

∴ 0.0143 mol of NaCl produce → 0.0143 mol of AgCl.

  • Now, we can get the mass of puree NaCl in the sample:

mass of pure NaCl = (no. of moles of pure NaCl)(molar mass of NaCl) = (0.0143 mol)(58.44 g/mol) = 0.8357 g.

∴ The percentage of NaCl in the impure sample = [(mass of pure NaCl)/(mass of the impure sample)] x 100 = [(0.8357 g)/(0.8421 g)] x 100 = 99.24%.

4 0
3 years ago
If the concentration of mercury in the water of a polluted lake is 0.250 μg (micrograms) per liter of water, what is the total m
aleksandr82 [10.1K]

Answer:

142.36 kg

Explanation:

volume of water in the lake = surface area x depth

= 18.5 x ( 1760 x 3 )² x 39 ft³

= 2.011 x 10¹⁰ ft³

= 2.011 x 10¹⁰ x 28.3168 liter .

= 56.945 x 10¹⁰ liter .

concentration of mercury = .25 x 10⁻⁶ g / liter

= 25 x 10⁻⁸ g / liter

= 25 x 10⁻¹¹ kg / liter

mass of mercury in the water of lake

= 25 x 10⁻¹¹ x 56.945 x 10¹⁰ kg

= 142.36 kg .

8 0
3 years ago
The substance on which the enzyme acts is called the _____ chemical.
Serga [27]

Answer:

the answer is A

Explanation:

it is substrates because ,Enzymes are specialized proteins that catalyze or speed up chemical reactions within cells. The substance upon which an enzyme acts is called a substrate. Substrates are small molecules.

8 0
3 years ago
Sulfur dioxide, SO2(g), can react with oxygen to produce sulfur trioxide, SO3(g), by the following reaction
WITCHER [35]

Answer:

The heat produced is -15,1kJ

Explanation:

For the reaction:

2SO₂+O₂ → 2SO₃

The enthalpy of reaction is:

ΔHr = 2ΔHf SO₃ - 2ΔHf SO₂

As ΔHf SO₃ = -395,7kJ and ΔHf SO₂ = -296,8kJ

<em>ΔHr = -197,8kJ</em>

Using n=PV/RT, the moles of reaction are:

n = \frac{1,00atm*3,75L}{0,082atmL/molK*298,15K} = <em>0,153 moles of reaction</em>

As 2 moles of reaction produce -197,8kJ of heat, 0,153moles produce:

0,153mol×\frac{-197,8kJ}{2mol} = <em>-15,1kJ</em>

<em></em>

I hope it helps!

8 0
3 years ago
If gas is initially at 350L and 500k then changes to 295K what is the new volume
Dimas [21]
<h2>Hello!</h2>

The answer is:

The new volume is equal to 206.5 L.

<h2>Why?</h2>

To solve this problem, we need to assume that the pressure is constant, and use the Charle's Law equation, so, solving we have:

\frac{V_1}{T_1}=\frac{V_2}{T_2}

We are given:

V_1=350L\\T_1=500K\\T_2=295K

Then, using the Charle's Law equation, we have:

\frac{350L}{500K}=\frac{V_2}{295K}

\frac{350L}{500K}=\frac{V_2}{295K}\\\\V_2=\frac{350L}{500K}*295K=206.5L

Hence, we have that the new volume is equal to 206.5 L.

Have a nice day!

5 0
3 years ago
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