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3 years ago

A globe is placed on your desk and you are asked to identify its physical properties. How would you describe the globe?

1 answer:

8 0

You could describe it's shape, color, varieties on sizes and shape of states, how it's rounded but with a top and bottom.

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Match the following associations. Exothermic or endothermic

Alekssandra [29.7K]

Answer:

1) ∆H is positive $\Rightarrow$ Endothermic

2) $E_p>E_r$ $\Rightarrow$ Endothermic

3) Energy is absorbed $\Rightarrow$ Endothermic

4) $E_r>E_p$ $\Rightarrow$ Exothermic

5) ∆H is negtive $\Rightarrow$ Exothermic

Explanation:

∆H is called as enthalpy change

It is also called as Heat of reaction

Energy is required for the bond to break a bond.

Energy is released when a bond is formed.

$H_2+Cl_2>2HCl$

that is

$H-H+Cl-Cl>2H-Cl$

We see in this equation, bonds between hydrogen and chlorine molecules gets broken and on the right side bond is formed in HCl.

If energy of products greater than energy of reactants then the reaction enthalpy change is endothermic .

If energy of products lesser than energy of reactants then the reaction enthalpy change is exothermic .

For example

$\Delta H=E_p-E_r$

$=30KJ-20KJ$

$=+10KJ$

(positive hence endothermic)

$\Delta H=E_p-E_r$

$=10KJ-40KJ$

$=-30KJ$

(negative hence exothermic)

8 0

4 years ago

Balance the following reaction. A coefficient of "1" is understood. Choose option "blank" for the correct answer if the

Vera_Pavlovna [14]

2NH₂ + O₂ → N₂ + 2H₂O

Explanation:

Balancing the equation means, the number of atoms on both sides of the equation must be the same.

In the case of the given equation, we have to find out whether it is balanced or not.

2NH₂ + O₂ → N₂ + 2H₂O

Atoms Number of atoms before balancing after balancing

LHS RHS LHS RHS

N 1 2 2 2

H 2 2 4 4

O 2 1 2 2

To balance the N atoms, we have to put 2 in front of NH₂, and then to balance the H, O atoms, we have to put 2 in front of H₂O, so that each atom in left hand as well as right hand side of the equation was balanced.

8 0

4 years ago

A 6.1-kg solid sphere, made of metal whose density is 2600 kg/m3, is suspended by a cord. When the sphere is immersed in a liqui

deff fn [24]

Answer:

Density of the liquid = 1470.43 kg/m³

Explanation:

Given:

Mass of solid sphere(m) = 6.1 kg

Density of the metal = 2600 kg/m³

Thus volume of the liquid :

$Volume(V)=\frac{Mass(m)}{Density (\rho)}$

Volume of the sphere = 6.1 kg/2600 kg/m³ = 0.002346 m³

The volume of water displaced is equal to the volume of sphere (Archimedes' principle)

Volume displaced = 0.002346 m³

Buoyant force = $\rho\times gV$

Where

$\rho$ is the density of the fluid

g is the acceleration due to gravity

V is the volume displaced

The free body diagram of the sphere is shown in image.

According to image:

$mg=\rho\times gV+T$

Acceleration due to gravity = 9.81 ms⁻²

Tension force = 26 N

Applying in the equation to find the density of the liquid as:

$6.1\times 9.81=\rho\times 9.81\times 0.002346+26$

$33.841=\rho\times 9.81\times 0.002346$

$\rho=\frac{33.841}{9.81\times 0.002346}$

$\rho=1470.43 kgm^3$

Thus, the density of the liquid = 1470.43 kg/m³

6 0

4 years ago

When water reacts with potassium metal the hydrogen produced ignites explosively on the surface of water .What cause the ignitio

Julli [10]

Answer:

Pottasium reacts with water vigorously and the reation is exothermic. The heat released causes the hydrogen released to ignite

Explanation:

7 0

3 years ago

Calculate the formula unit mass of CaCl2

melomori [17]

Formula unit mass is defined as the sum of the mass of all the atoms each multiplied its atomic masses that are present in the empirical formula of a compound. It is expressed in amu.

Atomic mass of calcium = 40 amu

Atomic mass of chlorine = 35.5 amu

Formula mass of CaCl2 = (1 x 40) + (2 x 35.5) = 111amu.

3 0

3 years ago