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3 years ago

Help please science (7th grade)

Chemistry

2 answers:

hoa [83]3 years ago

8 0

Answer:

Explanation:

Don't mind the random letters

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tiny-mole [99]3 years ago

8 0

Answer:

Explanation:

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What is the pH of a solution that has a [OH^-] of 1x10^-2? 2 12 9 8

ehidna [41]

The answer you are looking for is 9

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3 years ago

Use Le Châtelier's principle to predict how the equilibrium for the weak base methylamine responds to the indicated changes. CH

Anarel [89]

The question is incomplete, here is the complete question:

Use Le Châtelier's principle to predict how the equilibrium for the weak base methylamine responds to the indicated changes.

$CH_3NH_2(aq.)+H_2O(l)\rightleftharpoons CH_3NH_3^+(aq.)+OH^-(aq.);\Delta H^o_{rxn}=103kJ/mol$

1) adding KOH

2) Increasing the temperature

Answer:

For 1: The reaction will shift in left direction that is towards the reactants.

For 2: The reaction will shift in right direction that is towards the product.

Explanation:

For the given chemical equation:

$CH_3NH_2(aq.)+H_2O(l)\rightleftharpoons CH_3NH_3^+(aq.)+OH^-(aq);\Delta H^o_{rxn}=103kJ/mol$

We are given:

$\Delta H^o_{rxn}=103kJ/mol$

As, enthalpy of the reaction is positive. So, it is an endothermic reaction.

For an endothermic reaction, heat is getting absorbed during a chemical reaction and is written on the reactant side.

$A+\text{heat}\rightleftharpoons B$

Any change in the equilibrium is studied on the basis of Le-Chatelier's principle. This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.

For 1: Adding KOH

As, hydroxide ions are present on the product side of the reaction. So, when more hydroxide ion is added, the concentration of hydroxide ion increases on the product side.

According to Le-Chatelier's principle, to minimize the effect, the equilibrium will shift in the direction where hydroxide ion concentration decreases, which is to the reactant side.

Hence, the reaction will shift in left direction that is towards the reactants.

For 2: Increasing the temperature

As, heat is getting absorbed during a chemical reaction. This means that temperature is getting increased on the reactant side. If the temperature in the equilibrium is increased, the equilibrium will shift in the direction where, temperature is getting decreased.

Hence, the reaction will shift in right direction that is towards the product.

3 0

3 years ago

What characteristic of a solid is most responsible for their structure

amm1812

1. BONDING PATTERNS BETWEEN ATOMS.

2. TYPES OF MATTER IN SOLIDS.

Solids generally have their constituent particles arranged in a pattern known as crystalline structure. The crystalline structure of the solid is due to the types of matter and the chemical bonds that exist between the particles of solids. The constituent particles of a solid can be atoms, ions or molecules.

4 0

4 years ago

9 How many grams of O₂ are needed to produce 15.5 g Fe₂O3 in the following reaction? Fe(s) + O₂(g) → Fe₂O3 (s)

Slav-nsk [51]

Answer:

Explanation:

so u can work out the amount of moles in FeO3 by doing mr of fe3o3 is 55.8*3+16*3=215.4

moles= mass/mr so you do 15.5g/215.4=0.0719 moles

then using 1 to 1 ratio so O2 moles is 0.0719

then use the equation mass=mole*mr

so 0.0719*16=1.15g

hope this make sense :)

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3 years ago

the half-life of chromium 51 is 28 days if the sample contained 510 grams how much chromium would remain after 86 days

Anni [7]

Answer: 3.285714285714286 I believe this is what it is

Explanation:

You have to divide 50 by 28 then times it by 510 then divide by 86

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3 years ago