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Sati [7]
3 years ago
11

Why must sample spots be above the solvent in paper chromatography

Chemistry
1 answer:
marishachu [46]3 years ago
6 0
Because if they are submerged in the solvent, they would dissolve! This would prevent them from seperating and not allow you to actually record anything
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Is the following a chemical change or a physical change?
spayn [35]
It's a Chemical Change
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3 years ago
If the reactants have a potential energy of 10.2 kJ/mol and the products have a potential
Citrus2011 [14]

Answer:

The ΔH is 5.5 kJ/mol and the reaction is endothermic.

Explanation:

To calculate the ∆H (heat of reaction) of the combustion reaction, that is, the heat that accompanies the entire reaction, you must make the total sum of all the heats of the products and of the reagents affected by their stoichiometric coefficient ( number of molecules of each compound participating in the reaction) and finally subtract them:

Combustion enthalpy = ΔH = ∑H products - ∑Hreactants

In this case:

ΔH = 15.7 kJ/mol - 10.2 kJ/mol= 5.5 kJ/mol

An endothermic reaction is one whose enthalpy value is positive, that is, the system absorbs heat from the environment (ΔH> 0).

<u><em>The ΔH is 5.5 kJ/mol and the reaction is endothermic.</em></u>

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Explanation:

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Read 2 more answers
What is the maximum amount of HCl, in grams, that can be produced if 37.5 g of BCl3 and 60.0 g of H2O are reacted according to t
Rus_ich [418]
Ooooh boy alright. So, this may or may not be a limited reactant problem so we need to first find out of it is.

First, how many moles of each substance are there

the molar mass of BCl3 is <span>117.17 grams so 37.5 g / 117.17 is ~ .32 mol.
The molar mass of H2O is 18.02 so 60 / 18.02 is ~ 3.33 mol.

Now, for every 1 mole of BCl3, there are 3 moles of HCl created. Therefore, BCl3 can create ~ .96 moles.
For every 3 moles of H2O, there are 3 moles of HCl created. Therefore, HCl can create ~3.33 moles.

But, there is not enough BCl3 to support that 3.33 moles, only enough for .96 moles, therefore BCl3 is the limiting reactant. Now, to answer the question, simply multiply .96 moles by the molar mass of HCl.

.96 x 36.46 = ~35 g</span>
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3 years ago
QUICKEST GETS BRAINLIEST AND 7 POINTS
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Hello there.

Thomson's atomic model is best described by which of the following statements?

A nucleus with electrons moving around it like planets.
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3 years ago
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