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Tanzania [10]
3 years ago
9

How did oxygen come up to make 21% of the earth's present atmosphere?

Chemistry
1 answer:
MakcuM [25]3 years ago
4 0
Tiny organisms known as cyanobacteria, or blue-green algae.
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2. Balance the equation below, and answer the following question: What volume of chlorine gas, measured at STP, is needed to com
Juliette [100K]
Balanced equation: 2Na(s) + Cl₂(g) ---> 2NaCl(s)

when we have STP conditions, we can use this conversion: 1 mol = 22.4 L

first, we have to convert grams to molecules using the molar mass, and then use mole to mole ratio from the balanced equation. 

molar mass of Na= 23.0 g/mol
 ratio: 2 mol Na= 1 mol Cl₂ (based on coefficients of balanced equation)

calculations:

6.25 g Na ( \frac{1 mol Na}{23.0 g} ) ( \frac{1 mol Cl_2}{2 mol Na} ) ( \frac{22.4 L}{1 mol} )= 3.04 L
8 0
3 years ago
10 moles of carbon dioxide has a mass of 440 g. What is the relative formula mass of carbon dioxide?
Ksenya-84 [330]

Answer: 44g

Explanation: The formular for finding Moles is ;

Moles =  Mass / Molar Mass or Formular Mass.

Base on this question; Moles = 10, Mass = 440g, and Formular Mass = ?

Making 'Formular Mass', subject of the formular; we thus have;

Formular mass = Mass / Moles = 440/ 10 = 44g

7 0
3 years ago
The state of matter in which molecules are attracted to each other but can change position is a
slavikrds [6]

i believe the answer is a liquid

4 0
3 years ago
What elements is iodine made out of?
Thepotemich [5.8K]
Elements of iodine are fluorine, chlorine, bromine, and astatine.
8 0
3 years ago
Nitrogen and hydrogen combine to form ammonia in the Haber process. Calculate (in kJ) the standard enthalpy change ∆H° for the r
Kazeer [188]

Answer:

∆H° rxn = - 93 kJ

Explanation:

Recall that a change in standard in enthalpy, ∆H°, can be calculated from the inventory of the energies, H, of the bonds  broken minus bonds formed (H according to Hess Law.

We need to find in an appropiate reference table the bond energies for all the species in the reactions and then compute the result.

              N₂ (g)   +            3H₂ (g)   ⇒                          2NH₃ (g)

1 N≡N = 1(945 kJ/mol)     3 H-H = 3 (432 kJ/mol)       6 N-H = 6 ( 389 kJ/mol)

∆H° rxn = ∑  H bonds broken  - ∑ H bonds formed

∆H° rxn = [ 1(945 kJ)   + 3 (432 kJ) ] - [ 6 (389 k J]

∆H° rxn = 2,241 kJ -2334 kJ = -93 kJ

be careful when reading values from the reference table since you will find listed N-N bond energy (single bond), but we have instead a triple bond,  N≡N,  we have to use this one .

8 0
3 years ago
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