All categories

4 years ago

What % of all the atoms in the universe are hydrogen

Chemistry

1 answer:

irga5000 [103]4 years ago

5 0

Answer:

Over ninety percent of all the atoms in the Universe are hydrogen atoms.

Explanation:

Over ninety percent of all the atoms in the Universe are hydrogen atoms. By mass, hydrogen makes up about 75% of all matter in the Universe. Hydrogen atoms are also the smallest and lightest of all the atoms with only one electron and one proton in a common single hydrogen atom (called protium).

You might be interested in

What type of hydrocarbon is CH3-CH2-O-CH2-CH3? Is it a diethyl ether?

Nadusha1986 [10]

You are correct! this molecule is an ether, specifically diethyl ether.

5 0

3 years ago

(a) Write the dissolution reaction for solid Na2CO3 below. (Use the lowest possible coefficients. Include states-of-matter under

Andreas93 [3]

Answer:

For a: The chemical equation for the dissolution of sodium carbonate is $Na_2CO_3(s)\rightarrow Na_2CO_3(aq.)$

For b: The net acid-base reaction is $CO_3^{2-}(aq.)+H_2O(l)\rightarrow OH^-(aq.)+HCO_3^-(aq.)$

Explanation:

For a:

Dissolution reaction is defined as the reaction in which a solid compound gets dissolved in water to form aqueous solution.

The chemical equation for the dissolution of sodium carbonate follows:

$Na_2CO_3(s)\rightarrow Na_2CO_3(aq.)$

Ionization reaction is defined as the reaction in which an ionic compound dissociates into its ions when dissolved in aqueous solution.

The chemical equation for the ionization of sodium carbonate follows:

$Na_2CO_3(aq.)\rightarrow 2Na^+(aq.)+CO_3^{3-}(aq.)$

For b:

Now, the anion formed which is $CO_3^{2-}$ reacts with water to form conjugate acid.

The chemical equation for the reaction of anion with water follows:

$CO_3^{2-}(aq.)+H_2O(l)\rightarrow OH^-(aq.)+HCO_3^-(aq.)$

Hence, the net acid-base reaction of the anion formed and water is written above.

3 0

3 years ago

A) Write the word equation for the reaction of barium nitride (Ba3N2) with potassium.

artcher [175]

Answer:

Explanation:

In order to balance it, we need to have the same number of atoms of each element on both sides of the equation. There are two atoms of nitrogen on the left, so we need to put 2 in front of K₃N. Now, we have six atoms of potassium on the right, so we need to put 6 in front of K on the left. Finally, there are three atoms of barium on the left, so we put 3 before Ba on the tight. Which means:

Ba₃N₂ + 6K = 2K₃N + 3Ba

Now, we can do the work. First, we determine the molar mass of each reactant ( from the periodic table). Molar mass of the barium is 137, potassium 39 and nitrogen 14.

Ba₃N₂₂ has molar mass of 3Ba and 2N, which means 3 • 137 + 2 • 14 = 439. That means that one mole of Ba₃N₂ weights 439 grams.

We are given grams of reactants, but in order to find the limiting and the excess reactant, we need to transfer it into moles.

We are given 66.5 grams of Ba₃N₂ and we know that 439 grams equals 1 mole. We want to know how many moles there are in 66.5 grams, so the answer is 66.5 / 439 = 0.15 moles.

Let's do the same for potassium. We are given 29 grams of K and we know that 1 mole has 39 grams. We want to know how many moles of K are there in 29 grams, so the answer is 29 / 39 = 0.74 moles.

We now know that 0.15 moles of Ba₃N₂ reacted with 0.74 moles of K. From the balanced equation we see that 1 mole of Ba₃N₂ reacts with 6 moles of K, so the ratio has to be 1:6.

Now let's find limiting and excess reactant. That means that in our reaction, there are more (or less) of one reactant then needed.

We know that we had 0.15 moles of Ba₃N₂ reacting. Let's pretend we don't know the moles of K and let's see with which amount of K should 0.15 moles of barium nitride react, if the ratio is 1:6.

0.15 moles of Ba₃N₂ : x moles of K = 1:6

x = 0.9 moles of K

So, for the completed reaction we need to have 0.9 moles of K, but we previously calculated that we had 0.74. That means that there is less K then needed, so potassium is our limiting reactant, which obviously means that Ba₃N₂ is our excess reactant.

Now, we need to find how many moles of Ba₃N₂ there needed to be for a completed reaction

x moles of Ba₃N₂ : 0.74 moles of K = 1:6

x = 0.124 moles of Ba₃N₂

So we needed to have 0.124 moles, but we had 0.15 of Ba₃N₂, which is 0.15 - 0.124 = 0.026 moles in excess.

If we want to find how many grams that is, we only multiply it with molar mass of Ba₃N₂:

0.026 • 439 = 11.4 grams

That means that only 66.5 - 11.4 = 55.1 grams of Ba₃N₂ reacted.

3 0

3 years ago

A 68-kg man whose average body temperature is 39°C drinks 1 L of cold water at 3°C in an effort to cool down. Taking the average

Dmitry [639]

Answer:

<h3>The man's average body temp. will fall by 0.6°C to 38.4°C</h3>

Explanation:

The enthalpy (heat content) of the water, using a datum of 0°C, is

Hw = Mw kg x Cp,w (specific heat capacity kJ/kg °C) x Tw °C

= 1 kg x 4.18 kJ/kg°C x 3°C = 12.5 kJ

Hman (pre drink) = 68 kg x 3.6 kJ/kg/°C x 39°C = 9547 kJ

So Hman (post drink) = H (pre drink) + Hw = 9547 + 12.5 = 9559.5 kJ because no heat is lost immediately.

But Hman (after drink) has mass 68 + 1 = 69 kg

Also his new Cp will be approx (3.6 x 68/69) + (4.18 x 1/69) = 3.608 kJ/kg°C

So Hman = 9559.5 kJ (from above) = 69 kg x 3.608 kJ/kg°C x Tnew

Therefore the man's new overall temp. = 38.4°C which is a drop of 0.6°C

8 0

3 years ago

How many moles of oxygen react with 12 moles of aluminum

mina [271]

Answer:

If, for example, we want to know how many moles of oxygen will react with 17.6 mol ... Write the balanced chemical reaction for the combustion of C 5H 12

Explanation:

8 0

3 years ago