Given equation : 
Given information = 2.47 grams KNO2 and excess KMnO4 and we need to find grams of water (H2O).
Since KMnO4 is in excess, so grams of water(H2O) can be calculated using grams of KNO2 with the help of stoichiometry.
To find grams of water(H2O) from grams of KNO2 , we need to follow three steps.
Step 1. Convert 2.47 grams of KNO2 to moles of KNO2.
Molar mass of KNO2 = 85.10 g/mol
Moles = 0.0290 mol KNO2
Step 2. Convert moles of KNO2 to moles of H2O using mole ratio.
Mole ratio are the coefficient present in front of the compound in the balanced equation.
Mole ratio of KNO2 : H2O is 5 : 3 (5 coefficient of KNO2 and 3 coefficient of H2O)
Mole = 0.0174 mol H2O
Step 3. Convert mole of H2O to grams of H2O
Grams = Moles X molar mass
Molar mass of H2O = 18.00 g/mol
Grams of water = 0.313 grams H2O
Summary : The above three steps can also be done in a singe setup as shown below.
In the above setup similar units get cancelled out and we will get grams of H2O as 0.313 grams water (H2O)
We use the following formula to calculate the number of atoms:
n (mol) = N(number of atoms) / NA
N(He) = n(mol) · NA
N(He) = 2,0 moles · 6.02·1023 = 12.04·1023 atoms
Answer:Ithink erosion cuz if we can tell how long ago it eroded we can see how old it is
Explanation:
Answer:
D =Average atomic mass = 10.801 amu.
5) True
Explanation:
Abundance of B¹⁰= 19.9%
Abundance of B¹¹ = 80.1%
Atomic mass of B¹⁰ = 10 amu
Atomic mass of B¹¹ = 11 amu
Average atomic mass = ?
Solution:
Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) / 100
Average atomic mass = (10×19.9)+(11×80.1) /100
Average atomic mass = 199 + 881.1 / 100
Average atomic mass = 1080.1 / 100
Average atomic mass = 10.801 amu.
2)A chemical reaction is one in which a new elements is created
True
False
Answer:
In chemical reaction new substances are created.
For example:
Photosynthesis:
It is the process in which in the presence of sun light and chlorophyll by using carbon dioxide and water plants produce the oxygen and glucose.
Carbon dioxide + water + energy → glucose + oxygen
water is supplied through the roots, carbon dioxide collected through stomata and sun light is capture by chloroplast.
Chemical equation:
6H₂O + 6CO₂ + energy → C₆H₁₂O₆ + 6O₂
it is known from balanced chemical equation that 6 moles of carbon dioxide react with the six moles of water and created one mole of glucose and six mole of oxygen.
