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2 years ago

What are the 4 physical changes you can observe?

2 answers:

8 0

1. ice melting

2. temperature going down at night 

3. water evaporating (like a towel drying out) or water drop on the sink 

4. dew forming on the mirror after a shower

iren2701 [21]2 years ago

6 0

1. ice melting

2. ripping paper

3. dew on mirror because of shower

4. breaking glass

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POINTS AND BRAINIEST ANSWER!!!!

denis23 [38]

Answer:

hydrgen = i think it is 4

oxygen = i think it is 3

Explanation:

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3 years ago

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Hydrogen gas is filled in a 224 ml glass container at 0 degree celcius and 1 atmospheric pressure. What are the number of molecu

Step2247 [10]

Answer:

$\boxed{\text{6.02 $\math{\times 10^{21}}$ molecules}}$

Explanation:

A pressure of 1 atm and a temperature of 0 °C is the old definition of STP. Under these conditions, 1 mol of a gas occupies 22.4 L.

1. Calculate the moles of hydrogen.

$n = \text{0.224 L} \times \dfrac{\text{1 mol}}{\text{22.4 L}} = \text{0.0100 mol}$

2. Calculate the number of molecules

$\text{No. of molecules} = \text{0.0100 mol} \times \dfrac{\text{6.022 $\times 10^{23}$ molecules}}{\text{1 mol}}\\\\= \textbf{6.02 $\mathbf{\times 10^{21}}$ molecules}\\\\\text{The sample contains }\boxed{\textbf{6.02 $\mathbf{\times 10^{21}}$ molecules}}$

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3 years ago

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23. The reaction

Sindrei [870]

Answer:

b mi disputa se eu não asetar

6 0

2 years ago

The standard enthalpy change for the following reaction is 873 kJ at 298 K.

Flura [38]

Answer: - 436.5 kJ.

Explanation:

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation.

The given chemical reaction is,

$2KCl(s)\rightarrow 2K(s)+Cl_2(g)$ $\Delta H_1=873kJ$

Now we have to determine the value of $\Delta H$ for the following reaction i.e,

$K(s)+\frac{1}{2}Cl_2(g)\rightarrow KCl(s)$ $\Delta H_2=?$

According to the Hess’s law, if we divide the reaction by half then the $\Delta H$ will also get halved and on reversing the reaction , the sign of enthlapy changes.

So, the value $\Delta H_2$ for the reaction will be: