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3 years ago

8

Where does the energy for almost all ecosystems come from

1 answer:

bonufazy [111]3 years ago

4 0

The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs.

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A solution of HNO3 has a [H+] concentration of 0.001 M. What is the pH of point

Citrus2011 [14]

Answer:

3

Explanation:

pH=-log(H+)

- Hope that helps! Please let me know if you need further explanation.

7 0

3 years ago

Find the standard enthalpy of formation of ethylene, C2H4(g), given the following data: C2H4(g) + 3 O2(g) --> 2CO2(g) + 2 H2O

Brums [2.3K]

Answer : The standard enthalpy of formation of ethylene is, 52.4 kJ

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 formation reaction of $C_2H_4$ will be,

$2C(s)+2H_2(g)\rightarrow C_2H_4(g)$ $\Delta H_{formation}=?$

The intermediate balanced chemical reaction will be,

(1) $C_2H_4(g)+3O_2(g)\rightarrow 2CO_2(g)+2H_2O(l)$ $\Delta H_1=-1411kJ$

(2) $C(s)+O_2(g)\rightarrow CO_2(g)$ $\Delta H_2=-393.5kJ$

(3) $H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(l)$ $\Delta H_3=-285.8kJ$

Now we will reverse the reaction 1, multiply reaction 2 and 3 by 2 then adding all the equation, we get :

(1) $2CO_2(g)+2H_2O(l)\rightarrow C_2H_4(g)+3O_2(g)$ $\Delta H_1=+1411kJ$

(2) $2C(s)+2O_2(g)\rightarrow 2CO_2(g)$ $\Delta H_2=2\times (-393.5kJ)=-787kJ$

(3) $2H_2(g)+2O_2(g)\rightarrow 2H_2O(l)$ $\Delta H_3=2\times (-285.8kJ)=-571.6kJ$

The expression for enthalpy of formation of $C_2H_4$ will be,

$\Delta H_{formation}=\Delta H_1+\Delta H_2+\Delta H_3$

$\Delta H=(+1411kJ)+(-787kJ)+(-571.6kJ)$

$\Delta H=52.4kJ$

Therefore, the standard enthalpy of formation of ethylene is, 52.4 kJ

7 0

3 years ago

Three separate 3.5g blocks of al, cu, and fe at 25°c each absorb 0.505 kj of heat. which block reaches the highest temperature?

77julia77 [94]

The energy can be shown as:

Q = ms dT

Whereas, m is the mass of block

s is specific heat

dT is change in temperature.

Copper block having the lowest specific heat and thus having the higher change in temperature and therefore having the higher final temperature.

8 0

3 years ago

How do we determine the number of electrons in a neutral atom?

Elodia [21]

this is the answer of your question .

<em>Hope</em><em> </em><em>it</em><em> </em><em>helped </em><em>you</em>

3 0

3 years ago

Balance the chemical equation: <br> KOH + H3AsO4 → K2HAsO4 + H2O

Colt1911 [192]

2 <span>KOH +1 H3AsO4 →1 K2HAsO4 + 2 H2O</span>

3 0

3 years ago