How is it that life on earth has changed over million of years yet the Earth has not?

1 answer:

amm18123 years ago

5 0

When earth first formed it was likely composed of hydrogen, helium and other gases that contained hydrogen but it didnt last for very long because the solar wind from the sun blew it away solar wind is stream of charged particles such as electrons, protons, and aloha particles. We now have a magnatic field surrounding earth that sheilds us from the solar wind

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How many grams of oxygen are in a half a cup of water

USPshnik [31]

Answer: 2.78 moles of molecular oxygen will occupy 62.22 liters.

Explanation:

8 0

3 years ago

When aluminum, AlAl, metal is dipped in an aqueous solution of hydrochloric acid, HClHCl, hydrogen gas, H2H2, is produced with t

kifflom [539]

Answer:

Balanced equation: $2Al(s)+6HCl(aq.)\rightarrow 2AlCl_{3}(aq.)+3H_{2}(g)$

Explanation:

Al is an metallic species with a standard reduction potential of -1.66 V( $E_{Al^{3+}\mid Al}^{0}=-1.66V$ ).
$H_{2}$ is present at the intermediate position in electrochemical series with a standard reduction potential of 0 V ( $E_{H^{+}\mid H_{2}}^{0}=0V$ ).

So, when Al is dipped in aqueous solution of HCl, Al is readily oxidized to produce $Al^{3+}$ whereas $H^{+}$ is reduced to $H_{2}$ .
Hence, as a whole, aqueous $AlCl_{3}$ and gaseous $H_{2}$ is produced as products.

Balanced equation: $2Al(s)+6HCl(aq.)\rightarrow 2AlCl_{3}(aq.)+3H_{2}(g)$

5 0

4 years ago

Can somebody please help me with this question, I'm very confused! I thought i did it right because i found Kb and the conc. of

andrew-mc [135]

Let's investigate the substances involved in the reaction first. The compound <span>CH3NH3+Cl- is a salt from the weak base CH3NH2 and the strong acid HCl. When this salt is hydrated with water, it will dissociate into CH3NH2Cl and H3O+:

CH3NH3+Cl- + H2O </span>⇒ CH3NH2Cl + H3O+

Nest, let's apply the ICE(Initial-Change-Equilibrium) table where x is denoted as the number of moles used up in the reaction:

CH3NH3+Cl- + H2O ⇒ CH3NH2Cl + H3O+
Initial 0.51 0 0
Change -x +x +x
-------------------------------------------------------------------------------
Equilibrium 0.51 - x x x

Then, let's find the equilibrium constant of the reaction. Since the reaction is hydrolysis we use KH, which is the ratio of Kw to Ka or Kb. Kw is the equilibrium constant for water hydrolysis which is equal to 1×10⁻¹⁴. Since the salt comes from the weak base, we use Kb. Since pKb = 3.44, then. 3.44 = -log(Kb). Thus, Kb = 3.6307×10⁻⁴

KH = Kw/Kb = (x)(x)/(0.51 - x)
1×10⁻¹⁴/ 3.6307×10⁻⁴ = x²/(0.51-x)
x = 3.748×10⁻⁶

Since x from the ICE table is equal to the equilibrium concentration of H+, we can find the pH of the aqueous solution:

pH = -log(H+) = -log(x)
pH = -log ( 3.748×10⁻⁶)
pH = 5.43

6 0

3 years ago

Pls help, How is stoichiometry used to calculate amounts of substances in a chemical reaction?

Elden [556K]

Answer:

Thus, to calculate the stoichiometry by mass, the number of molecules required for each reactant is expressed in moles and multiplied by the molar mass of each to give the mass of each reactant per mole of reaction. The mass ratios can be calculated by dividing each by the total in the whole reaction.

Explanation: Stoichiometry is the field of chemistry that is concerned with the relative quantities of reactants and products in chemical reactions. For any balanced chemical reaction, whole numbers (coefficients) are used to show the quantities (generally in moles ) of both the reactants and products.

7 0

3 years ago

Why does ch3ch2ch2cl have a lower boiling point than ch3ch2ch2oh?

Damm [24]

Perhaps because of the chlorine atom

3 0

3 years ago