Answer: 
Explanation:
Significant figures : The figures in a number which express the value or the magnitude of a quantity to a specific degree of accuracy is known as significant digits.
Rules for significant figures:
Digits from 1 to 9 are always significant and have infinite number of significant figures.
All non-zero numbers are always significant.
All zero’s between integers are always significant.
All zero’s after the decimal point are always significant.
All zero’s preceding the first integers are never significant.
Thus has three significant figures
The reaction formula of this is C3H8 + 5O2 --> 3CO2 + 4H2O. The ratio of mole number of C3H8 and O2 is 1:5. 0.025g equals to 0.025/44.1=0.00057 mole. So the mass of O2 is 0.00057*5*32=0.0912 g.
Answer:
a) 381.2 g
b) 39916 g
c) 0.0013 lb mol
d) 29.6 g mol
Explanation:
The molecular weight (mw) of a compound is the mass of it per mole, so it's the ratio of the mass (m) per mole (n).
a) The molecular weight of one mol is found at the periodic table. So, for Mg, mw = 24.3 g/mol, for Cl = 35.5 g/mol, so for MgCl2, mw = 24.3 + 2*35.5 = 95.3 g/mol. The g mol is the mass divided by the molecular weight:
g mol = m/mw
4 = m/95.3
m = 381.2 g
b) The pound (lb) is a unity of mass, and the lb mol is a unity of the mass divided by the molecular weight. So, by the periodic table, the molecular weight of C3H8 is 3*12 (of C) + 8*1 (of H) = 44 lb/mol.
lb mol = m/mw
2 = m/44
m = 88 lb
1 lb = 453.592 g
So, m = 88*453.592 = 39916 g
c) The molecular weight of N2 is 2*14 (of N) = 28 lb/mol.
m = 16/453.592 = 0.0353 lb
lb mol = m/mw
lb mol = 0.0353/28
lb mol = 0.0013 lb mol
d) The molecular weight is 2*12 (of C) + 6*1(of H) + 1*16(of O) = 46 g/mol
3 lb = 1360.78 g
g mol = m/mw
g mol = 1360.78/46
g mol = 29.6 g mol
Total number of atoms in the sample is the sum of number of atoms of all the elements present in the sample.
Number of gold, 
atoms in 
= 
atoms (given)
From the formula of compound that is it is clear that the number of potassium and gold are same whereas those of carbon and nitrogen are 2 times of them.
So, the number of atoms of each element is:
Number of potassium, 
atoms in = atoms
Number of carbon, 
atoms in = 
atoms = 
Number of nitrogen, 
atoms in = atoms =
Total number of atoms in = Number of gold, atoms+Number of potassium, atoms +Number of carbon, atoms + Number of nitrogen, atoms
Total number of atoms in = 
Total number of atoms in = 
atoms
Hence, the total number of atoms in is 
atoms.
Answer:
2 electrons are transfered in this reaction.
Explanation:
Oxidation is a reaction where an atom, ion, or molecule loses electrons, while reduction corresponds to the electron gain of an atom, ion, or molecule.
In an oxidation-reduction reaction two simultaneous processes take place, oxidation and reduction.
So, oxidation-reduction (redox) reactions involve the transfer of electrons between chemical species. They are also called electron transfer reactions since the particle that is exchanged is the electron.
In this case:
Zn(s) ⇒ Zn²⁺(aq) + 2 e⁻
2 Ag⁺ (aq) + 2 e⁻ ⇒ 2 Ag(s)
So, zinc metal loses two electrons to form the zinc(II) ions, while the two silver ions each gain one electron to form two silver metal atoms.
Then, Zn is a reducing agent (The reducing agent is the one that provides the electrons, oxidizing itself), AgNO3 is an oxidizing agent (The oxidizing agent is the one that traps the electrons, reducing itself).
Finally, you can see that <u><em>2 electrons are transfered in this reaction.</em></u>
