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Anna007 [38]
3 years ago
12

PLEASE HELP!!! Which of John Dalton's contributions are present in the modern atomic model and which were eventually disproven a

nd thus are not part of the modern model??? If you have any questions please don't ask in the answer box.
Chemistry
1 answer:
Yanka [14]3 years ago
5 0
1) All matter is made of atoms. Atoms are indivisible and indestructible.

2) All atoms of a given element are identical in mass and properties

3) Compounds are formed by a combination of two or more different kinds of atoms.

4) A chemical reaction is a rearrangement of atoms.

1 and 2 were proved wrong.
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Refer to a periodic table. In which period is calcium?<br> 6<br> 4<br> 2<br> 8
kvasek [131]

Here look at this image it might help you if not then i will see what i can help you with

6 0
3 years ago
Anyone tryna help mee
devlian [24]

Answer:

It is a solid

4 0
3 years ago
If 25.0 mL of 0.451 M NaOH solution is titrated with 0.253 M H2SO4, the flask at the endpoint will contain (besides the indicato
tigry1 [53]

Answer:

H₂O, Na⁺, and SO₄²⁻

Explanation:

NaOH and H₂SO₄ are strong electrolytes. They will ionize completely .

Molecular equation:          2NaOH + H₂SO₄ ⟶ Na₂SO₄ + 2H₂O

Ionic equation: 2Na⁺ + 2OH⁻ + 2H⁺ + SO₄²⁻ ⟶  2Na⁺ + SO₄²⁻+ 2H₂O

  • The concentration of water is 55.5 mol·L⁻¹.
  • The concentration of Na⁺ is twice that of SO₄²⁻ .
  • Hydrolysis of SO₄²⁻ is negligible.

The principal components in the flask at the endpoint are H₂O, Na⁺, and SO₄²⁻.

4 0
3 years ago
Calculate the no. of each atoms presents in 10 grams of calcium carbonate.
raketka [301]

Molar Mass of Calcium carbonate:-

\\ \sf\longmapsto CaCO_3

\\ \sf\longmapsto 40u+12u+3(16u)

\\ \sf\longmapsto 52u+48u

\\ \sf\longmapsto 100u

\\ \sf\longmapsto 100g/mol

  • Given Mass=10g

\boxed{\sf No\:of\;moles=\dfrac{Given\:Mass}{Molar\:Mass}}

\\ \sf\longmapsto No\:of\;moles=\dfrac{10}{100}

\\ \sf\longmapsto No\:of\:moles=0.1mol

Now

\boxed{\sf No\:of\:molecules=No\;of\:moles\times Avagadro\: No}

\\ \sf\longmapsto 0.1\times 6.023\times 10^{23}

\\ \sf\longmapsto 6.023\times 10^{22}molecules

8 0
3 years ago
For which of the following reactions is S° &gt; 0. Choose all that apply. N2(g) + 3H2(g) 2NH3(g) 2C2H6(g) + 7O2(g) 4CO2(g) + 6H2
Lostsunrise [7]

Answer: 2C_2H_6(g)+7O_2(g)\rightarrow 4CO_2(g)+6H_2O(g)

NH_4I(s)\rightarrow NH_3(g)+HI(g)

2H_2O(g)+2SO_2(g)\rightarrow 2H_2S(g)+3O_2(g)

Explanation:

Entropy is the measure of randomness or disorder of a system.

A system has positive value of entropy if the disorder increases and a system has negative value of entropy if the disorder decreases.

1. N_2(g)+3H_2(g)\rightarrow 2NH_3(g)

As 4 moles of gaseous reactants are changing to 2 moles of gaseous products,  the randomness is decreasing and the entropy is negative

2. 2C_2H_6(g)+7O_2(g)\rightarrow 4CO_2(g)+6H_2O(g)

As 9 moles of gaseous reactants are changing to 10 moles of gaseous products,  the randomness is increasing and the entropy is positive.

3. NH_4I(s)\rightarrow NH_3(g)+HI(g)

As 1 mole of solid reactants is changing to 2 moles of gaseous products, the randomness is increasing and the entropy is positive.

4. 2H_2O(g)+2SO_2(g)\rightarrow 2H_2S(g)+3O_2(g)

As 4 moles of gaseous reactants is changing to 5 moles of gaseous products, the randomness is increasing and the entropy is positive

5. 2NO(g)+2H_2(g)\rightarrow N_2(g)+2H_2O(l)

As 4 moles of gaseous reactants is changing to 1 moles of gaseous products, the randomness is decreasing and the entropy is negative.

5 0
3 years ago
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