What is the only sure evidence for a chemical reaction?

How many atoms of carbon are represented in 3CH3CH2O? 2 4 6 8

GenaCL600 [577]

Answer: 6

Explanation:

1) The structure shown is:

3CH₃CH₂O

2) The molecule is CH₃CH₂O. The chemical formula is CH₃CH₂O. The subscripts indicate the number of atoms of the corresponding atom in each molecule.

Then, there are 1 + 1 = 2 atoms of C, 3+ 2 = 5 atoms of H, and 1 atom of O.

3) The number in front of the molecule is the coefficient. It is 3, and it tells the number of molecules.

So, there are 3 molecules, which means that you have 3 times a many atoms as calculated previously.

That is 3×2 = 6 atoms of C, 3 × 5 = 15 atoms of H, and 3 × 1 = 3 atoms of O.

Then, the number of atoms of carbon (C) in 3 molecules is 6

4 0

3 years ago

Convert the composition of the following alloy from atom percent to weight percent (a) 44.9 at% of silver, (b) 46.3 at% of gold,

vesna_86 [32]

Answer:

Mass percentage of gold : 33.35%

Mass percentage of silver: 62.80%

Mass percentage of copper : 3.85%

Explanation:

$N=n\times N_A$

Where : N = Number of atoms

n = moles

$N_A=6.022\times 10^{23}$ = Avogadro number

Let the total atoms present in the alloy be 100.

Atom percentage of silver = 44.9%

Atoms of of silver = 44.9% of 100 atoms = 44.9

Atomic weight of silver = 107.87 g/mol

Mass of 44.9 silver atoms = 107.87 g/mol × 44.9 = 4,843.363 g/mol

Atom percentage of gold= 46.3%

Atoms of of gold = 46.3% of 100 atoms = 46.3

Atomic weight of gold = 196.97 g/mol

Mass of 44.9 gold atoms = 196.97 g/mol × 46.3 = 9,119.711 g/mol

Atom percentage of copper = 8.8 %

Atoms of of copper = 8.8% of 100 atoms = 8.8

Atomic weight of copper = 63.55 g/mol

Mass of 44.9 copper atoms = 63.55 g/mol × 8.8 = 559.24 g/mol

Total mass of an alloy :4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol

Mass percentage of gold :

$\frac{4,843.363 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=33.35 \%$

Mass percentage of silver:

$\frac{9,119.711 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=62.80\%$

Mass percentage of copper :

$\frac{559.24 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=3.85\%$

7 0

3 years ago

PLEASE HELP ME WITH THIS I WILL GIVE YOU POINTS

eduard

Answer:

1. a

2. c

3. b

4. f

5. d

6. e

Explanation:

7 0

3 years ago

Let us assume that fe(oh)2(s) is completely insoluble, which signifies that the precipitation reaction with naoh(aq) (presented

Yuki888 [10]

17.8 mL NaOH

Step 1. Write the chemical equation

Fe^(2+) + 2NaOH → Fe(OH)2 + 2Na^(+)

Step 2. Calculate the moles of Fe^(2+)

Moles of Fe^(2+) = 500 mL Fe^(2+) × [0.0230 mmol Fe^(2+)]/[1 mL Fe^(2+)]

= 11.50 mmol Fe^(2+)

Step 3. Calculate the moles of NaOH

Moles of NaOH = 11.50 mmol Fe^(2+) × [2 mmol NaOH]/[1 mmol Fe^(2+)]

= 23.00 mmol NaOH

Step 4. Calculate the volume of NaOH

Volume of NaOH = 23.00 mmol NaOH × (1 mL NaOH/1.29 mmol NaOH)

= 17.8 mL NaOH

3 0

3 years ago

Benefits of using n2o as a refrigerant.

Murrr4er [49]

Mexican Texas is the historiographical name used to refer to the era of Texan history between 1821 and 1836, when it was part of Mexico. Mexico gained independence from Spain in 1821 in its war ofindependence. Initially, Mexican Texas operated very similarly to Spanish Texas.

5 0

3 years ago