Answer:
The atomic weight of Rubidium (Rb) is 85.91 amu, using 4 significant figures.
Explanation:
The average atomic mass of Rubidium (Rb) is composed by the mass of the two given isotopes 85^Rb and 87^Rb but each isotope has a different abundance in nature expressed by percentage (natural occurrence).
Therefore, we need to calculate how much of this mass with its abundance percentage contribute to the average atomic mass for each isotope.
First step: Calculate the contribution in mass using the natural occurrence percentage.
85^Rb = 84.91 × 
= 61.73 amu
87^Rb = 86.91 ×
= 24.18 amu
The answers for each isotope are given using a typical percentage formula.
Second step: Add the two mass values founded.
24.18 amu + 61.73 amu = 85.91 amu
Third Step: Check the significant figures
The answer is 85.91 amu and it has 4 significant figures.
Answer:
3NH₄OH + H₃PO₄ → (NH₄)₃PO₄ + 3H₂O
Products are water and ammonium phosphate
Explanation:
This is a neutralization between a weak base and a weak acid where the products are water and the correspondent salt.
Base: NH₄OH → NH₄⁺ + OH⁻
Acid : H₃PO₄ → 3H⁺ + PO₄⁻³
H⁺ bonds to OH⁻ to make H₂O → As we have 3 protons, we can make 3 moles of water, so there are needed 3 OH⁻.
Phosphate has -3 as oxidation state, then it needs 3 ammonium to form the salt.
The balanced equation is:
3NH₄OH + H₃PO₄ → (NH₄)₃PO₄ + 3H₂O
<span>To compare the energy of microwaves, IR-B, and IR-A, we need to compare how long the wavelengths are for each wave. Through the intervals given, we can determine that we in order from greatest to least energy, the order is IR-A, IR-B, microwaves.</span>
Answer:
540
Explanation:
i added them and then the result is out
The answer is; C
Conservation of matter in a reaction means that the mass of matter in the products is equal to the mass of the reactants. Energy/matter cannot be created or destroyed but converted from one form to another.
An expanding balloon with the increased evolution of gas is a good visible practical sign in the experiment on the conservation of matter in the reaction. As the magnesium disappears with an increased input of hydrochloric acid, the balloon gets bigger showing that more hydrogen is evolved from the reaction;
2HCL + Mg MgCl2 + H2
