When does the composition of a substance does not change?

To gain an idea as to how many atoms are in a gram or so of copper, use the larger balance

anygoal [31]

Answer:

Explanation:

To solve this problem, we must understand the relationship between mass of a substance and the number of atoms.

Atoms are the smallest indivisible particles of any matter. A substance can be made up of several number of atoms in their space.

The mass of any substance is a function of the amount of atoms its contains.

The mass of a substance is related in chemistry to the amount of atoms its contains using the parameter called the number of moles.

A mole is the amount of substance that contains the Avogadro's number of particles. This number is 6.02 x 10²³ particles. The particles here can be protons, neutrons, electrons, atoms e.t.c.

Now,

Number of moles = $\frac{mass}{molar mass}$

Molar mass of copper = 63.6g/mole

Number of moles = $\frac{2}{63.6}$ = 0.03mole

Since 1 mole of a substance contains 6.02 x 10²³atoms

0.03 mole of copper will contain 0.03 x 6.02 x 10²³atoms

= 1.89 x 10²² atoms

He needs to add 1.89 x 10²² atoms to make 2g of the sample.

7 0

3 years ago

Given that this reaction is exothermic, what direction will the equilibrium shift when the temperature of the reaction is decrea

Svetradugi [14.3K]

Equilibrium will shift towards the products when temperature is decreased in an exothermic reaction of the formation of ammonia.

<h3>What is an exothermic reaction?</h3>

An exothermic reaction is a reaction in which heat content of the reactants is greater than the heat content of product.

In an exothermic reaction, heat is given off.

For an exothermic reaction in equilibrium, increasing temperature shifts equilibrium to the towards the left, towards the reactants.

On the other, equilibrium will shift towards the products when temperature is decreased.

Therefore, equilibrium will shift towards the products when temperature is decreased in the reaction of the formation of ammonia.

Learn more about exothermic reactions at: brainly.com/question/13892884

#SPJ1

7 0

2 years ago

An earthworm is slithering on a sidewalk towards a grassy lawn which organelles activity contributes most directly to muscle con

givi [52]

Answer:

3. Mitochondria

Explanation:

Numerous mitochondria are found in each muscle cell to provide metabolic energy for muscle contraction.

hope i helped (:

5 0

2 years ago

Explain how changing the concentration The enthalpy change for the reaction, 3CO (g) 2Fe2O3 (s) Imported Asset Fe(s) 3CO2 (g), c

ycow [4]

Answer: For the given equation, only iron has the value of $\Delta H_f$ equal to 0 kJ.

Explanation:

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as $\Delta H^o$

The equation used to calculate enthalpy change is of a reaction is:

$\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f(product)]-\sum [n\times \Delta H^o_f(reactant)]$

For the given chemical reaction:

$3CO(g)+2Fe_2O_3(s)\rightarrow Fe(s)+3CO_2(g)$

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

$\Delta H^o_{rxn}=[(1\times \Delta H^o_f_{(Fe(s))})+(3\times \Delta H^o_f_{(CO_2(g))})]-[(3\times \Delta H^o_f_{(CO(g))})+(2\times \Delta H^o_f_{(Fe_2O_3(s))})]$