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Molecular Mass

Molecular mass measures the mass of a molecule. It is measured by adding together the atomic masses of atoms the molecule is made of.

1,424 Questions
Chemistry
Atoms and Atomic Structure
Molecular Mass

What is the mass of 3.8 moles of Na?

Sodium is a metal element. Mass of 3.8 moles is 87.4g.

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles of sodium hydroxide will be produced from the complete reaction of 15.0 g sodium?

Sodium reacts with water. 0.652 NaOH moles will form.

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Chemistry
Atoms and Atomic Structure
Molecular Mass

What is the mass of 7 moles of strontium?

7 moles of strontium is equal to 613,34 g.

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles of aluminum are in 10.8 grams?

10,8 g aluminium is equivalent to 0,4 moles.

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles of CO are produced from 5 moles o2?

The answer is 10 moles of carbon monoxide.
2 C + O2 = 2 CO

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Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles of HCl are needed to react 2.4 moles of Al?

This reaction emmits H2 gas. We need 7.2 moles of Hcl.

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles of HCl and needed to react 2.4 moles of Al?

Al+HCl===> AlCl3+H2 Is the reaction. You need &.2 moles of HCl.

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

According to the ideal gas laws what happens to the volume of a gas when the number of moles doubles?

The product PV remain constant in a closed system at constant temperature.

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles are in 750 L of hydrogen gas?

750 L hydrogen gas at 0 0C and 1 at is equal to 33,44 moles.

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

How do we get moles from mass?

Calculate:

mass/molar mass = moles

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Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles of CC14 are present in 56g?

This is carbon tetra chloride. there are 0.3636 moles in this mass.

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Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles are in 45g of F?

45 g is equal to 1,184 moles fluorine.

012
Chemistry
Molecular Mass

How many moles in 20 grams of Na2CO3?

20 g anhydrous sodium carbonate is equivalent to 0,188 moles.

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Chemistry
Atoms and Atomic Structure
Molecular Mass

What form of the ideal gas law would you use to calculate the number of moles?

This is the general law of gases:
PV = nRT (n is the number of moles)

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

What is the pressure of 4 moles of helium in a 50l tank at 308 K?

The pressure is approx. 2 atmospheres.

012
Elements and Compounds
Molecular Mass

What is the molecular mass for MgO?

When there is only one atomic symbol shown for each element in the formula of a compound, as with MgO, the molecular mass is simply the sum of the gramatomic masses, in this instance, 40.304 grams.

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles of hydrogen are in C2H6?

Ethane contain 20 % hydrogen.

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

What volume of hydrogen in L is produced from the complete reaction of 3.143 moles of hydrogen chloride with magnesium at STP Mg s 2 HCl aq MgCl2 aq H2 g?

The reaction is 2HCl(aq) + Mg(s) ==> MgCl2(aq) + H2(g)
3.143 moles HCl will yield 1/2 x 3.143 moles of H2 gas (see balanced equation stoichiometry)
Thus, 3.143 moles/2 = 1.5715 moles H2 gas will be produced
At STP 1 mole - 22.4 liters, thus 1.5715 moles x 22.4 L/mole = 35.20 liters of H2 gas formed

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles of KF are contained in 347 g of water in a 0.175 m KF solution?

The definition of 0.175 m KF is that 1 kg of water contains 0.175 moles of KF. Thus, 347 g of water is equivalent to 0.347 kg, and to find moles of KF, you calculate as follows:
0.175 moles/Kg x 0.347 kg = 0.0607 moles of KF are present (3 significant figures).

012
Chemistry
Atoms and Atomic Structure
Molecular Mass

How many moles of gold Au are in 3.60X10-5 of gold?

If 3,6 x 10-5 is grams the number of atoms is 1,1.10e17.

012
Units of Measure
Physics
Chemistry
Molecular Mass

Does gas have mass and density?

The short answer is yes, gas has mass and density. However, you should note that gas is a state of matter, just as solid and liquid are. Since all matter has mass, any substance in its gaseous state has mass. Since all matter occupies space, it has density, since density is defined as mass per unit volume, where volume is space.

Larger objects dont always have more mass than smaller objects.

202122
Chemistry
Atoms and Atomic Structure
Molecular Mass

How many grams of oxygen will be required to produce 25 moles of sulfur dioxide?

Sulfur dioxide is SO2, so there are 2 moles of oxygen for each mole of sulfur. In 25 moles of SO2, there are 25 moles of S, so there must be 50 moles of oxygen, or 25 moles of diatomic oxygen gas (O2).

001
Units of Measure
Molecular Mass

What would be the unit to use to measure a single molecule?

the term gram molecule was used in chemistry and this unit is used to measure a single molecule in gram molecule.

001
Chemistry
Organic Chemistry
Elements and Compounds
Molecular Mass

What is the molar mass of chlorine?

The atomic weight of chlorine (after IUPAC 2009) is [35,446;35,457].

The rounded molar mass is 35,45 g/mol, to 4 significant figures.

So the molar mass of chlorine (Cl2 molecule) will be 70.90 g/mol

232425
Chemistry
Elements and Compounds
Molecular Mass

How do you find the molecular formula of a compound?

It's very easy. First of all we test the given sample in laboratory to know about its constitution. Let's discuss it by taking an example:-

Suppose the constitution of a compound is given as below:-

C = 92.4%, H = 7.6%

let's assume that the sample is 100 gram. so the weight of carbon is 92.4 gram & that of hydrogen is 7.6 gram. Now it's we must make sure that is the total of weights of constituents 100 or not? If it is not 100, it means there is an another element in the compound, and this is always oxygen in case of hydrocarbons.

Step 1st :- Find out the number of moles of each element

number of moles = weight of the element/atomic mass

number of moles of C = 92.4/12 = 7.7 moles

number of moles of H = 7.6/1 = 7.6 mole

Step 2nd:- Find out the relative ratio of the moles:- It is simply done by dividing all by the smallest one

C = 7.7/7.6 = 1.01

H = 7.6/7.6 = 1

Step 3rd:- If the ratio is not whole numbers the multiply all the numbers by a smallest integer number to make them whole numbers.

Here in this case both are nearly whole numbers. so there is need to multiply these numbers.

C = 1

H = 1

Step 4th:- Write the empirical formula

C1H1

step 5th:- Find the weight of empirical formula

1*12 + 1*1 = 13

now if the molecular weight is given then the molecular formula can be written easily.

molecular weight = ( empirical formula weight)n

for example the molecular weight is 78.

n = 78/13 = 6

so the molecular formula is = C6H6

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