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GREYUIT [131]
2 years ago
13

A white powder is added to a solution. The images show observations made before the powder is added, just after the powder has b

een added, and a little while later. (The liquid in the small beaker is phenol red solution.) What evidence shows that a chemical change has taken place?
Chemistry
2 answers:
7nadin3 [17]2 years ago
6 0

There was a change in its color from white to red which can only be changed by a chemical reaction

makvit [3.9K]2 years ago
5 0

D.All of above. Hope it helps!!!

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If the kinetic energy of a particle is equal to twice its rest mass, what is the velocity of the particle? Determine if relativi
ivann1987 [24]

Answer:

The velocity of the particle is 2 m/s,

Explanation:

Kinetic energy is defined as energy of the body due to its motion. It is given by :

K.E=\frac{1}{2}mv^2

Where :

m = mass of the object

v = velocity of the object

We have , particle with mass m and its kinetic energy is twice its mass.

K.E=2m

2m=\frac{1}{2}mv^2

v^2=\frac{4}{1}

v=2

And unit of velocity are m/s , so the velocity of the particle is 2 m/s.

8 0
2 years ago
g When 2.50 g of methane (CH4) burns in oxygen, 125 kJ of heat is produced. What is the enthalpy of combustion (in kJ) per mole
Anna [14]

Answer:

-800 kJ/mol

Explanation:

To solve the problem, we have to express the enthalpy of combustion (ΔHc) in kJ per mole (kJ/mol).

First, we have to calculate the moles of methane (CH₄) there are in 2.50 g of substance. For this, we divide the mass into the molecular weight Mw) of CH₄:

Mw(CH₄) = 12 g/mol C + (1 g/mol H x 4) = 16 g/mol

moles CH₄ = mass CH₄/Mw(CH₄)= 2.50 g/(16 g/mol) = 0.15625 mol CH₄

Now, we divide the heat released into the moles of CH₄ to obtain the enthalpy per mole of CH₄:

ΔHc = heat/mol CH₄ = 125 kJ/(0.15625 mol) = 800 kJ/mol

Therefore, the enthalpy of combustion of methane is -800 kJ/mol (the minus sign indicated that the heat is released).

3 0
2 years ago
According to the following balanced reaction, how many moles of HNO3 are formed from 8.44 moles of NO2 if there is plenty of wat
kotegsom [21]

Answer:

5.63 mol.

Explanation:

  • The balanced chemical equation between NO₂ and H₂O is:

<em>3NO₂(s) + H₂O(l) → 2HNO₃(aq) + NO(g), </em>

It is clear that 3 mol of NO₂ reacts with 1 mol of H₂O to produce 2 mol of HNO₃ and 1 mol of NO.

<em>Water is present as an excess reactant and NO₂ is limiting reactant.</em>

<em></em>

  • To find the no. of moles of HNO₃ produced:

3 mol of NO₂ produces → 2 mol of HNO₃, from stichiometry.

8.44 mol of NO₂ produces → ??? mol of HNO₃.

∴ The no. of moles of HNO₃ are formed = (8.44 mol)(2 mol)/(3 mol) = 5.63 mol.

3 0
2 years ago
Zinc sulfide reacts with oxygen according to the reaction 2ZnS(s)+3O2(g)→2ZnO(s)+2SO2(g) A reaction mixture initially contains 5
LenKa [72]

Answer:

The answer to your question is: Excess oxygen = 2.3 mol

Explanation:

Data

ZnS = 5 mol

O2 = 9.8 mol

Excess reactant = ?

Balanced reaction

                                 2ZnS(s) + 3O2(g) → 2ZnO(s) + 2SO2(g)

MW ZnS = 65 + 32 = 97 x 2 = 194 g

MW O2 = 16 x  6 = 96 g

                           2 mol of ZnS  ------------------- 3 mol O2

 

Ratio from the reaction = 3 mol O2/ 2 mol ZnS

                                      = 1.5

Ratio from the quantities in the experiment = 9.8 mol O2 / 5 mol of ZnS

                                                                        = 1.96

Excess reactant = Oxygen because the ratio increases

                             

                                2 mol of ZnS  ------------------- 3 mol O2

                                5 mol of ZnS  -------------------  x

                                x = (5 x 3) / 2

                               x = 7.5 mol of O2

Excess Oxygen = 9.8 mol - 7.5 mol

Excess oxygen = 2.3 mol

4 0
2 years ago
What impact would adding twice as much Na2 CO3 than required for stoichiometric quantities have on the quantity of product produ
IrinaK [193]

Answer:

There will be no observed impact of adding twice as much Na2CO3 on the product

Explanation:

Stoichiometry gives the relationship between reactants and products in terms of mass, mole and volume.

If we consider the stoichiometry of the reaction, we will discover that the reaction occurs in a 1:1 ratio. This implies that use of twice the amount of Na2CO3 will only lead to an excess of Na2CO3 making the other reactant the limiting reactant. Once the other reactant is used up, the reaction quenches.

Hence, use of twice as much Na2CO3 has no impact on the quantity of product produced.

5 0
2 years ago
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