Answer:
A neutron is a subatomic particle with a mass comparable to a proton and a neutral electrical charge. A neutron is a subatomic particle with a mass of 1 and charge of 0. ... While the number of protons in a atom determines its element, the number of neutrons determines its isotope
Explanation:
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Amount of Niobium-91 initially
= 300/91 =3.2967mol
2040 years = 3 ×680 = 3 half-lives
therefore, amount left = 0.4121mol
mass of Niobium-91 remaining = 0.4121 ×91 =37.5g
Answer: 126.1 grams of are needed to make 5.3 L of 0.25 M solution
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.
To calculate the mass of solute for given molarity, we use the equation:
Thus 126.1 grams of are needed to make 5.3 L of 0.25 M solution
The question is incomplete, the complete question is;
When 1 mole of P4O10(s) reacts with H2O(l) to form H3PO4(aq) according to the following equation, 453 kJ of energy are evolved.
P4O10(s) + 6H2O(l)When 1 mole of P4O10(s) reacts4H3PO4(aq)
Is this reaction endothermic or exothermic? _________endothermicexothermic
Answer:
The reaction is exothermic
Explanation:
An exothermic reaction refers to any reaction in which heat was EVOLVED. The word was stressed to indicate that it holds the key to answering the question correctly.
We were told in the question that heat was evolved, hence the reaction is exothermic in nature.
The balanced thermochemical equation of the reaction is :
P₄O₁₀(s) + 6H₂O(l) → 4H₃PO₄(aq) ____ ΔH = -453 kJ
