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Gwar [14]
3 years ago
9

How many block shells are the d block and the f block​

Chemistry
1 answer:
HACTEHA [7]3 years ago
4 0

Answer:

1s, 3p, 5d, 7f

Explanation:

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You have a vial that may contain lead(II) cations or barium cations, but not both. Available to you are solutions of ammonium su
Bess [88]

Answer:

We should add, the KBr solution.

Explanation:

The vial contains Ba²⁺  and Pb²⁺

Our solutions are: (NH₄)₂ SO₄, NaF and KBr

We dissociate the solutions:

(NH₄)₂ SO₄  → 2NH₄⁺ + SO₄⁻²

NaF → Na⁺ + F⁻

KBr → K⁺ + Br-

When we add ammonium sulfate and sodium fluorine, we are adding sulfates and fluorines, but these two anions make precipitate both cations, we can not determine, if the vial contains Ba²⁺ or Pb²⁺

SO₄⁻²(aq) + Ba²⁺ (aq) → BaSO₄ (s)  ↓

SO₄⁻² (aq)+ Pb²⁺(aq)  → PbSO₄ (s)  ↓

2F⁻ (aq) + Ba²⁺ (aq) → BaF₂ (s) ↓

2F⁻ (aq) + Pb²⁺ (aq) → PbF₂ (s)  ↓

When we add the KBr, bromides only make precipitate with Pb²⁺, so the vial has only Pb²⁺ cation:

2Br⁻ (aq) + Ba²⁺ (aq) → BaBr₂ (aq)

2Br⁻ (aq) + Pb²⁺ (aq) → PbBr₂ (s) ↓

3 0
3 years ago
28. How many formula units are found in 0.250 moles of potassium nitrate?
Soloha48 [4]

Answer:

\boxed {\boxed {\sf B. \ 1.5 *10^{23} \ formula \ units}}

Explanation:

1 mole of any substance contains the same number of particles. The particles can vary (atoms, molecules, formula units), but there are always 6.022*10²³ particles. In this case, the particles are formula units of potassium nitrate or KNO₃.

Let's create a ratio.

\frac {6.022*10^{23} \ formula \ units  \ KNO_3}{1 \ mol \ KNO_3}

Since we are trying to find the formula units in 0.250 moles, we multiply by that number.

0.250 \ mol \ KNO_3 *\frac {6.022*10^{23} \ formula \ units  \ KNO_3}{1 \ mol \ KNO_3}

The units of moles of potassium nitrate cancel.

0.250  *\frac {6.022*10^{23} \ formula \ units  \ KNO_3}{1 }

The denominator of 1 can be ignored, so we can make a simple multiplication problem.

0.250  *{6.022*10^{23} \ formula \ units  \ KNO_3}

1.5055 * 10^{23} \ formula \ units \ KNO_3

If we round to the nearest tenth, the 0 in the hundredth place tells us to leave the 5 in the tenth place.

1.5 *10^{23} \ formula \ units \ KNO_3

0.250 moles of potassium nitrate is approximately equal to 1.5*10²³ formula units of potassium nitrate and choice B is correct.

7 0
3 years ago
Rewrite each equation below with the delta H value included with either the reactants or the products and identify the reaction
yanalaym [24]
A) 2H₂(g) + O₂(g) → 2H₂O(l) + 285.83 kJ
Exothermic

B) 2Mg + O₂ → 2MgO + 1200kJ
Exothermic
5 0
3 years ago
What is the percentage composition of each element in hydrogen peroxide, H2O2?
Degger [83]

Answer:

The percentage composition of each element in H2O2 is 5.88% H and 94.12% O (Option D).

Explanation:

Step 1: Data given

Molar mass of H = 1.0 g/mol

Molar mass of O = 16 g/mol

Molar mass of H2O2 = 2*1.0 + 2*16 = 34.0 g/mol

Step 2: Calculate % hydrogen

% Hydrogen = ((2*1.0) / 34.0) * 100 %

% hydrogen = 5.88 %

Step 3: Calculate % oxygen

% Oxygen = ((2*16)/34)

% oxygen = 94.12 %

We can control this by the following equation

100 % - 5.88 % = 94.12 %

The percentage composition of each element in H2O2 is 5.88% H and 94.12% O (Option D).

8 0
3 years ago
Read 2 more answers
Which property is NOT used to separate a mixture?
NeTakaya

Answer: ability to undergo a chemical reaction

Explanation:

6 0
3 years ago
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