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2 years ago

You have 4.72x10^25 atoms of a substance with MW of 136.94 g/mol How many moles do you have

Chemistry

1 answer:

slega [8]2 years ago

4 0

Number of moles = 78.41

<h3>Further explanation </h3>

The mole is the number of particles(molecules, atoms, ions) contained in a substance

1 mol = 6.02.10²³ particles

Can be formulated

N=n x No

N = number of particles

n = mol

No = Avogadro's = 6.02.10²³

4.72 x 10²⁵ atoms of a substance, then moles :

$\tt n=\dfrac{N}{No}\\\\n=\dfrac{4.72\times 10^{25}}{6.02\times 10^{23}}\\\\n=78.41$

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A flask is filled with 50.0 ml of 0.15 M HCl acid. Exactly 0.054 grams of CaCo3 are placed in the acid,

ira [324]

Answer:

See explanation

Explanation:

2HCl(aq) + CaCO3(aq) ------->CaCl2(aq) + CO2(g) + H2O(l)

Number of moles of acid present = 50/1000 * 0.15 = 0.0075 moles

Number of moles of calcium carbonate = 0.054g/100 g/mol = 0.00054 moles

2 moles of HCl reacts with 1 mole of calcium carbonate

x moles of HCl reacts with 0.00054 moles of calcium carbonate

x = 2 * 0.00054/1

x = 0.00108 moles of HCl

Amount of acid left = 0.0075 moles - 0.0075 moles = 0.00642 moles

Reaction of HCl and NaOH

HCl(aq) + NaOH(aq) ------> NaCl(aq) + H2O(l)

Since the reaction is in the mole ratio of 1:1

0.00642 moles of HCl is neutralized by 0.00642 moles of NaOH

8 0

2 years ago

Number of H in 3(NH4)2Cro4

zlopas [31]

The number of H atoms in 3(NH₄)₂CrO₄ = 24

<h3>Further explanation </h3>

The empirical formula is the smallest comparison of atoms of compound forming elements.

A molecular formula is a formula that shows the number of atomic elements that make up a compound.

(empirical formula) n = molecular formula

Subscripts in the chemical formula indicate the number of atoms

The compound of 3(NH₄)₂CrO₄ ( 3 molecules of (NH₄)₂CrO₄ ) :

Number of H :

$\tt 4\times 2(subscript)\times 3(coefficient,number~of~molecules)=24~atoms$

7 0

2 years ago

The decomposition of copper(II) nitrate on heating is endothermic reaction. 2Cu(NO3)2(s) → 2C10(s) + 4NO2(g) + O2(g) Calculate t

Basile [38]

Answer:

The enthalpy change for the given reaction is 424 kJ.

Explanation:

$2Cu(NO_3)_2(s)\rightarrow 2CuO(s) + 4NO_2(g) + O_2(g),\Delta H_{rxn}=?$

We have :

Enthalpy changes of formation of following s:

$\Delta H_{f,Cu(NO_3)_2}=-302.9 kJ/mol$

$\Delta H_{f,CuO}=-157.3 kJ/mol$

$\Delta H_{f,NO_2}= 33.2 kJ/mol$

$\Delta H_{f,O_2}= 0 kJ/mol$ (standard state)

$\Delta H_{rxn}=\sum [\Delta H_f(product)]-\sum [\Delta H_f(reactant)]$

The equation for the enthalpy change of the given reaction is:

$\Delta H_{rxn}$ =

$=(2 mol\times \Delta H_{f,CuO}+4\times \Delta H_{f,NO_2}+1 mol\times \Delta H_{f,O_2})-(2mol\times \Delta H_{f,Cu(NO_3)_2})$

$\Delta H_{rxn}$ =

$(2mol\times (-157.3 kJ/mol)+4\times 33.2 kJ/mol=1 mol\times 0 kJ/mol)-(2 mol\times (-302.9 kJ/mol)$

$\Delta H_{rxn}=424 kJ$

The enthalpy change for the given reaction is 424 kJ.

6 0

3 years ago

Which of the following is NOT a reason why chemical bonds are important? *

KengaRu [80]

Answer:

the answer would be B :)

3 0

3 years ago

The unique odors and flavors of many fruits are primarily due to small quantities of a certain class of organic compounds. The e

SpyIntel [72]

Based on the diagram shown, a numerical setup for calculating the gram-formula mass for reactant 1 would be :
6(1) + 2(12) + 16

Hope this helps

5 0

2 years ago