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3 years ago

How many atoms of gold are in 112 grams of gold?

1 answer:

3 0

Atomic mass gold = 196.96 u.m.a

196.96 g ------------------ 6.02x10²³ atoms
112 g ---------------------- ( atoms)

atoms = 112 x ( 6.02x10²³) / 196.96

atoms = 6.74x10²⁵ / 196.96

= 3.42x10²³ atoms

hope this helps!

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g A 500. mL solution contains 0.665 M NaC2H3O2 and 0.475 M HC2H3O2. What mass of HCl in grams needs to be added for the solution

77julia77 [94]

Answer:

7.38g HCl

Explanation:

Using H-H equation for acetic buffer:

pH = pKa + log [NaC2H3O2] / [HC2H3O2]

Where pKa is -log Ka = 4.74 and [] could be taken as moles of each compound.

The initial moles of each specie is:

[NaC2H3O2]:

0.500L * (0.665mol/L) = 0.3325moles

[HC2H3O2]:

0.500L * (0.475mol/L) = 0.2375 moles

That means total moles are:

[NaC2H3O2] + [HC2H3O2] = 0.57 moles (1)

And solving H-H equation for a pH of 4.21:

4.21 = 4.74 + log [NaC2H3O2] / [HC2H3O2]

0.29512 = [NaC2H3O2] / [HC2H3O2] (2)

Replacing (1) in (2):

0.29512 = 0.57mol - [HC2H3O2] / [HC2H3O2]

0.29512 [HC2H3O2] = 0.57mol - [HC2H3O2]

1.29512 [HC2H3O2] = 0.57mol

[HC2H3O2] = 0.44 moles

The HCl reacts with NaC2H3O2 producing HC2H3O2, that means you need to add:

0.44 moles - 0.2375 moles =

0.2025 moles of HCl

Using molar mass of HCl (36.45g/mol), to convert these moles to grams:

0.2025 moles * (36.45g/mol) =

8 0

3 years ago

In the disproportionation reaction CI2 + H2Omc021-1.jpgHCIO + HCI, what describes the oxidation states of the substance Cl?

Sophie [7]

Reaction: CI2 + H2O ----> HCIO + HCI

Oxidations states:

The oxitation state of Cl2 = 0, because the oxidation state of an atom alone or a molucule with one kind of atom is always 0.

The oxidation state of Cl in HClO is +1 because the oxidation state of H is + 1, the oxidation state of O is - 2, and the molecule is neutral, so +1 + 1 - 2 = 0

The oxidation state of Cl in HCl is - 1, because the oxidation state of H is +1 and the molecule is neutral, so - 1 + 1 = 0.

Also, you shall remember that when an atom increases its oxidation state is is oxidized and when an atoms reduces its oxidations state it is reduced.

With that you conclude that the right option is the last statement: Cl has an oxidation number of 0 in Cl2. It is then reduced to CI- with an oxidation number of –1 in HCl and is oxidized to Cl+ with an oxidation number +1 in HClO.

8 0

3 years ago

A reaction between 46 grams of sodium and 71 grams of chlorine formed table salt and heat.

vazorg [7]

Answer:

d. 117 grams

Explanation:

The mass of the table salt produced will be 117 grams.

Chemical reactions obey the law of conservation of mass. In this regard, matter is neither created nor destroyed in the course of a chemical reaction. It is expected that the mass of the reactants and products remain the same.

The reaction expression:

2Na + Cl₂ → 2NaCl

So, mass of sodium = 46g

mass of chlorine formed = 71g

Mass of NaCl = 46 + 71 = 117g

7 0

3 years ago

S + 6 HNO3 --> H2SO4 + 6 NO2 + 2 H2O

lina2011 [118]

Answer:

43.5 moles of HNO₃.

Explanation:

The balanced equation for the reaction is given below:

S + 6HNO₃ —> H₂SO₄ + 6NO₂ + 2H₂O

From the balanced equation above,

6 moles of HNO₃ reacted to produce 2 moles of H₂O.

Finally, we shall determine the number of mole of HNO₃ required to produce 14.5 moles of H₂O.

This can be obtained as illustrated below:

From the balanced equation above,

6 moles of HNO₃ reacted to produce 2 moles of H₂O.

Therefore, Xmol of HNO₃ will react to produce 14.5 moles of H₂O i.e

Xmol of HNO₃ = (6 × 14.5)/2

Xmol of HNO₃ = 43.5 moles

Therefore, 43.5 moles of HNO₃ is required to produce 14.5 moles of H₂O.

7 0

2 years ago

The element hydrogen is made up of which kind(s) of atoms?

sergey [27]

B. only hydrogen atoms

3 0

3 years ago

Read 2 more answers