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2 years ago

Where was all the hydrogen in the universe formed?

1 answer:

5 0

The low-mass elements, hydrogen and helium, were produced in the hot, dense conditions of the birth of the universe itself. The birth, life, and death of a star is described in terms of nuclear reactions. The chemical elements that make up the matter we observe throughout the universe were created in these reactions.

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Given that ΔH = −571.6 kJ/mol for the reaction 2 H2(g) + O2(g) → 2 H2O(l), calculate ΔH for these reactions. (a) 2 H2O(l) → 2 H2

pashok25 [27]

Answer : The value of $\Delta H$ for the reaction is +571.6 kJ/mole.

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction is,

$2H_2(g)+O_2(g)\rightarrow 2H_2O(l)$ $\Delta H_1=-571.6kJ/mole$

Now we have to determine the value of $\Delta H$ for the following reaction i.e,

$2H_2O(l)\rightarrow 2H_2(g)+O_2(g)$ $\Delta H_2=?$

According to the Hess’s law, if we reverse the reaction then the sign of $\Delta H$ change.

So, the value $\Delta H_2$ for the reaction will be:

$\Delta H_2=-(-571.6kJ/mole)$

$\Delta H_2=+571.6kJ/mole$

Hence, the value of $\Delta H$ for the reaction is +571.6 kJ/mole.

6 0

2 years ago

Cecil writes the equation for the reaction of hydrogen and oxygen below.

Wittaler [7]

Answer:

C) to show that atoms are conserved in chemical reactions

Explanation:

When writing a chemical reaction, we should always consider the Mass Conservation Law, which basically states that; in an isolated system; the total mass should remain constant, this is, the total mass of the reactives should be equal to the total mass of the products

For this case, we should add the apporpiate coefficients in order to be in compliance with this law:

2H₂ + O₂ → 2H₂O

So, we can check the above statement:

For reactives (left side):

For product (right side):

5 0

3 years ago

What is another name for a coefficient? this is for chemistry

krok68 [10]

Answer:

synergistic

Explanation:

Synergistic means: relating to the interaction or cooperation of two or more organizations, substances, or other agents to produce a combined effect greater than the sum of their separate effects

7 0

2 years ago

An experimental spacecraft consumes a special fuel at a rate of 372 L/min. The density of the fuel is 0.730 g/mL and the standar

Karolina [17]

Explanation:

First, we will calculate fuel consumption is as follows.

$372 L/min \times 1000 ml/L \times 0.730 g/ml \times \frac{1}{60} min/s$

= 4526 g/s

Now, we will calculate the power as follows.

Power = Fuel consumption rate × -enthalpy of combustion

= $4526 g/s \times -26.5 kJ/g$

= $1.19 \times 10^{5}$ kW

Thus, we can conclude that maximum power (in units of kilowatts) that can be produced by this spacecraft is $1.19 \times 10^{5}$ kW.

5 0

3 years ago

Two<br>moin tunetons of carbohydraus

inn [45]

Answer:

Carbohydrates can be divided into two main types: simple and complex. Simple carbohydrates are made up of just one or two sugar units, whereas complex carbohydrates are made up of many sugar units.

7 0

2 years ago