CHEMISTRY HIGH SCHOOL

What is mean by scientific approach in chemistry
brief it

Answers

Answer 1
Answer:

Answer:

scientific approach

Explanation:

Method of investigation in which a problems is First identified and observations, experiment are done

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I need to know the answer for number two. * I

Answers

Answer:

The answer to your question is (C). I would work out the question for you lad, but I don't know how to do it on here.

Explanation:

Calculate the number of moles 3.16 g of KMnO4 32.33 g of K2CrO4 100 g of KHCO3

Answers

The number of moles:
3.16g of KMnO_(4)
1 mole of KMnO_(4)- 158g.
x moles of KMnO_(4)- 3.16g.
x=(1\ mole*3.16g)/(158g)=(3.16)/(158)=0.02\ mole

The number of moles:
32.33g of K_(2)CrO_(4)
1 mole of K_(2)CrO_(4)- 194g.
x moles of K_(2)CrO_(4)- 32.33g.
x=(1\ mole*32.33g)/(194g)=(32.33)/(194)=0.17\ mole

The number of moles:
100g of KHCO_(3)
1 mole of KHCO_(3)- 100.1g.
x moles of KHCO_(3)- 100g.
x=(1\ mole*100g)/(100.1g)=(100)/(100.1)=0.999\ mole


Greetings, 
n00nst00p :)

What quantity of magnesium (in grams) is needed to supply the energy required to warm 30 mL of water (density = 1.00 g/mL) from 22°C to 90°C?

Answers

Answer:

0.22 grams of magnesium

This seems too low, so check the calculations/

Explanation:

How is the heat delivered?  Is the magnesium hot and added to the water?  If so, at what temperature.

Is the heat generated from an exothermic chemical reaction?

=================

I'll assume here that the heat comes from the reaction of magnesium with water.  The balanced equation is:

   Mg + 2H2O = Mg(OH)2 + H2

It has a heat of reaction of  −924.7 kJ/mol.

We need enough Mg to heat 30 ml of water from 22°C to 90°C.  The specific heat of water is needed.  It is 4.184 J/g-K.  It tells us that 4.184 Joules are needed to raise the temperature of water by 1 degree K.

30 ml of water with density 1 gram/ml means we have 30 grams of water.  (We'll ignore the water that is added from the chemical reaction.).

Lets calculate the Joules required to raise 30 grams of water from 22°C to 90°C.  Note that the specific heat has units of g and Kelvin.  Since we need a temperature change, the number value for ΔT is the same for both °C and °K.  So the temperature change is +68°K.

We can now calculate the Joules required:  

(30 grams H2O)*(4.184 J/g-K)*(+68°K)  = 8535.4 Joules or 8.5 kJ to 2 sig figs.

The Mg/H2O  heat of reaction of  −924.7 kJ/mol. will allow us to calculate the amount of Mg needed to supply 8.5 kJ.  The minus sign tells us that the reaction RELEASES energy (the energy leaves the "system" of Mg and H2O).  

Calculate the moles of Mg needed to release 8.5 kJ:

   (924.7 kJ/mole)*(x moles) = 8.5 kJ

x moles = 0.0092 moles

Whoa.  That is only (0.0092 moles)*(24.03 g/mole) = 0.22 grams of magnesium

This seems low to me, so check on the heat of reaction figure I used.  And don't let the hydrogen get away.  

   

What is the percent composition by mass of nitrogen in NH4NO3 (gram-formula mass = 80.0 grams/mole)?(1) 17.5% (3) 52.5%
(2) 35.0% (4) 60.0%

Answers

Answer:

The correct option is (2) 35.0%

Explanation:

If we want to calculate the percent composition by mass of nitrogen in NH4NO3 we first need to calculate the mass of nitrogen in one mole of NH4NO3.

Because of the molecular form of NH4NO3 (it has 2 ''N'') we know that one mole of NH4NO3 contains 2 moles of N.

The molar mass of N (nitrogen) is 14.0067(g)/(mole)

This means that 1 mole of N contains 14.0067 grams of N.

Because we have 2 moles of N ⇒ (2moles).(14.0067(g)/(mole))=28.0134g

We know that in 1 mole of NH4NO3 we have 2 moles of N(28.0134 g of N).

To calculate the percent composition by mass of nitrogen we need to divide the mass of nitrogen in one mole of NH4NO3 by the mass of one mole of NH4NO3 and then multiply it by 100.

We know that in 1 mole of NH4NO3 there are 80.0 g of NH4NO3 (Because of the molar mass data) ⇒

((28.0134g)/(80.0g)).100=35.016 % ≅ 35.0%

We find that the percent composition by mass of nitrogen in NH4NO3 is 35.0%

We conclude that the correct option is (2) 35.0%
gram-formula=80.0grams/mole will be 35.0%

Which of the following choices represents a balanced chemical equation? Ca3(PO4)2 + 6SiO2 → P4O10 + 3CaSiO3 2Ca3(PO4)2 + 6SiO2 → P4O10 + 6CaSiO3 2Ca3(PO4)2 + 3SiO2 → 2P4O10 + 2CaSiO3 3Ca3(PO4)2 + 2SiO2 → P4O10 + 4CaSiO3

Answers

2Ca_3(PO_4)_2 + 6SiO_2 -> P_4O_(10) + 6CaSiO_3 Hence, option B is correct.

What is a balanced equation?

A balanced equation is an equation for a chemical reaction in which the number of atoms for each element in the reaction and the total oxidation numbers is the same for both the reactants and the products.

2Ca_3(PO_4)_2 + 6SiO_2 -> P_4O_(10) + 6CaSiO_3 represents a balanced chemical equation.

Learn more about the balanced equation here:

brainly.com/question/7181548

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Here is the correct answer: 2Ca3(PO4)2 + 6SiO2 -> P4O10 + 6CaSiO3

Why does an ion have an electrical charge?

Answers

An ion has an electrical charge because it either has more electrons than protons or it has more protons than electrons. Electrons, which are found in the shells of an atom, have a negative charge, while protons, found in the atom's nucleus, have a positive charge.
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