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3 years ago

HELP PLEASE (If you cant answer all, that okay! First to answer all will be mark BRAINLIEST!)

Chemistry

1 answer:

Yakvenalex [24]3 years ago

4 0

Answer:

Hope this helps :)

Explanation:

Antoine Lavoisier- used patterns to predict undiscovered elements

John Newlands- Arranged elements according to their atomic

Johann Wolfgang- created groups of three elements, each based on Johann Wolfgang Dobereiner

Dmitri Mendeleev- divided elements into four categories

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The reaction CO2(g) → C(s) + O2(g) is a decomposition reaction. True False

Lyrx [107]

The reaction CO₂(g) → C(s) +O₂(g) is a decomposition reaction is true

Explanation

A Decomposition reaction is a reaction in which involve breaking down a compound into two or more simpler substances.

The reaction above is a decomposition reaction since CO₂ molecule is broken down into C (an element) and O₂ (a molecule).

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3 years ago

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Name Formula: Lead (II) Oxide F) Pb2O G) PbO2 H) PbO I) Pb2O2

garik1379 [7]

Answer:

PbO is the Answer

Explanation:

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3 years ago

How will the price of a product impact on the profits of the entrepreneur

taurus [48]

Answer:

The higher your price, the less volume you have to produce for a given dollar amount of profit! Even a small price increase can generate significant additional profit. ... When a business comes out with a new product or service and they are the first to market, they may be able to charge high prices initially.

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2 years ago

If the ph of a solution is decreased from ph 8 to ph 6 it means that the

saw5 [17]

Explanation:

Relation between pH and concentration of hydrogen ions is as follows.

pH = $-log [H^{+}]$

So, it means that an increase in the value of pH will show that there occurs a decrease in concentration of hydrogen ions.

Therefore, the solution becomes basic in nature.

On the other hand, a decrease in the value of pH will show that there occurs an increase in the concentration of hydrogen ions.

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Hence, if the pH of a solution is decreased from pH 8 to pH 6 it means that the concentration of hydrogen ions has increased in the solution.

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3 years ago

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Given the following data:

bagirrra123 [75]

$176.0 \; \text{kJ} \cdot \text{mol}^{-1}$

As long as the equation in question can be expressed as the sum of the three equations with known enthalpy change, its $\Delta H$ can be determined with the Hess's Law. The key is to find the appropriate coefficient for each of the given equations.

Let the three equations with $\Delta H$ given be denoted as (1), (2), (3), and the last equation (4). Let $a$ , $b$ , and $c$ be letters such that $a \times (1) + b \times (2) + c \times (3) = (4)$ . This relationship shall hold for all chemicals involved.

There are three unknowns; it would thus take at least three equations to find their values. Species present on both sides of the equation would cancel out. Thus, let coefficients on the reactant side be positive and those on the product side be negative, such that duplicates would cancel out arithmetically. For instance, $3 + (-1) = 2$ shall resemble the number of $\text{H}_2$ left on the product side when the second equation is directly added to the third. Similarly

$\text{NH}_4 \text{Cl} \; (s)$ : $-2 \; a = 1$
$\text{NH}_3\; (g)$ : $-2 \; b = -1$
$\text{HCl} \; (g)$ : $2 \; c = -1$

Thus

$a = -1/2\\b = 1/2\\c = -1/2$ and

$-\frac{1}{2} \times (1) + \frac{1}{2} \times (2) - \frac{1}{2} \times (3)= (4)$

Verify this conclusion against a fourth species involved- $\text{N}_2 \; (g)$ for instance. Nitrogen isn't present in the net equation. The sum of its coefficient shall, therefore, be zero.

$a + b = -1/2 + 1/2 = 0$

Apply the Hess's Law based on the coefficients to find the enthalpy change of the last equation.

$\Delta H _{(4)} = -\frac{1}{2} \; \Delta H _{(1)} + \frac{1}{2} \; \Delta H _{(2)} - \frac{1}{2} \; \Delta H _{(3)}\\\phantom{\Delta H _{(4)}} = -\frac{1}{2} \times (-628.9)+ \frac{1}{2} \times (-92.2) - \frac{1}{2} \times (184.7) \\\phantom{\Delta H _{(4)}} = 176.0 \; \text{kJ} \cdot \text{mol}^{-1}$

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3 years ago