Which description of nitrogen-15 is correct?

Chemistry

1 answer:

VashaNatasha [74]2 years ago

8 0

The first one is correct cause first of all it's atomic number is 7 and second of all it's atomic mass is about 15

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The reaction of Pb+4 and O-2 produces the compound of

vovikov84 [41]

Answer:

Pb₂O₄

Explanation:

The given species are:

Pb⁴⁺ O²⁻

Now, to solve this problem, we use the combining powers which corresponds to the number of electrons usually lost or gained or shared by atoms during the course of a chemical combination.

Pb⁴⁺ O²⁻

Combining power 4 2

Exchange of valencies 2 4

Now the molecular formula is Pb₂O₄

4 0

2 years ago

The combustion of ethene in the presence of excess oxygen yields carbon dioxide and water: c2h4 (g) + 3o2 (g) → 2co2 (g) + 2h2o

meriva

Answer:

$\boxed{-267.5}$

Explanation:

You can calculate the entropy change of a reaction by using the standard molar entropies of reactants and products.

The formula is

$\Delta_{r} S^{\circ} = \sum_n {nS_{\text{products}}^{\circ} - \sum_{m} {mS_{\text{reactants}}^{\circ}}}$

The equation for the reaction is

C₂H₄(g) + 3O₂(g) ⟶ 2CO₂(g) + 2H₂O(ℓ)

ΔS°/J·K⁻¹mol⁻¹ 219.5 205.0 213.6 69.9

$\Delta_{r} S^{\circ} = (2\times213.6 + 2\times69.9) - (1\times219.5 + 3\times205.0)\\\\= 567.0 - 834.5 = \boxed{-267.5 \text{ J}\cdot\text{K}^{-1} \text{mol}^{-1}}$