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adelina 88 [10]
3 years ago
15

Which of the following is a pure substance?

Chemistry
1 answer:
Mazyrski [523]3 years ago
8 0

Answer:

1. B

2. 100 C

3.  C

4. D

5. D

Explanation:

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The potential energy diagram for a reaction starts at 380 kJ and ends at 100 kJ. What type of reaction does the diagram best rep
ohaa [14]

Answer: A.  Exothermic reaction

Explanation: Enthalpy change for a reaction is sum of enthalpy of formation of products minus sum of enthalpy of formation of reactants.

When the energy level of reactants is above as compared to the products, the reaction is exothermic and when its opposite then reaction is endothermic.

From given information, the potential energy diagram starts at 380 kJ means the energy level of reactants is 380 kJ. It ends at 100 kJ means the energy of products is 100 kJ.

Enthalpy of reaction = 100 kJ - 380 kJ

Enthalpy of reaction = -280 kJ

Negative sign of enthalpy change indicates an Exothermic reaction.

5 0
3 years ago
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NEED HELP ASAPPP<br><br> What is the number of beryllium atoms in 78.0g of Be?
polet [3.4K]

Answer: number of atoms is 5.21 · 10^24

Explanation: Atomic mass of Be is 9.012 g/mol.

Number of moles n = m/M = 78.0 g / 9.012 g/mol =

Multiply this with Avogadro number Na = 6.022*10^23 1/mol

4 0
3 years ago
Why does ice float?​
Trava [24]

Ice is less dense than water. Hydrogen bonding makes water more dense than when it is in the form of ice!

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Rewrite the equation below using the correct conventions for stoichiometric coefficients. 2 BaCl2 + 2 H2SO4 → 2 BaSO4 + 4 HCl
vichka [17]

Answer:

BaCl2+H2SO4 \rightarrow BaSO4+2HCl

Explanation:

The given equation is:

2 BaCl2+2H2SO4 \rightarrow2BaSO4+4HCl

Based on the reaction stoichiometry:

2 moles of barium chloride (BaCl2) reacts with 2 moles of sulfuric acid (H2SO4) to form 2 moles of barium sulfate (BaSO4) and 4 moles of HCl

Although the reaction is balanced, the correct convention is to depict reactions in terms of the lowest molar ratio. Therefore the coefficients (2,2,4 and 4) can be divided by 2 to give:

BaCl2+H2SO4 \rightarrow BaSO4+2HCl

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3 years ago
Which is the empirical formula for a compound that contains 64.75g nitrogen and 185.25 oxygen
Svetach [21]

Answer:

What is the formula for a compound that contains 64.75 g nitrogen and 185.25 g oxygen? D. N2O5

The name of a hydrate is calcium chloride dihydrate. What is its formula? B. CaCl2 x 2H20

Explanation:

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5 0
3 years ago
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