Answer:
The reaction is exothermic and ΔH is negative
Explanation:
An exothermic reaction is a chemical reaction that releases energy in the form of heat. It is the opposite of an endothermic reaction in which energy is absorbed. It is expressed in a general thermochemical equation: reactants → products + energy.
We can know that a reaction is exothermic by observing the calorimeter to know if there is an increase in temperature. Remember that an exothermic reaction leads to evolution of heat. This is observed physically as a rise in temperature.
The calorimeter initially read 21.0 and finally read 38.8 at the end of the reaction. This implies that heat was given out in the process. The reaction is exothermic and ∆H is negative.
Mass = volume x density
volume = πr²
since Diameter = 2.5 cm
then radius = 1.25cm
∴ volume = π x (1.25cm)³
≈ 6.1359 cm³
Thus mass = 6.1359 cm³ x 11.34 g / cm³
= 69.58 g
Answer:
A.
Atoms cannot be created or destroyed by chemical reactions.
Explanation:
Metals=Reactivity increases as we move through the elements in the period table from top to bottom, and left to right. Nonmetals=Reactivity increases as we move through the elements in the periodic table, as we move from bottom to the top, and right to left. Since reactivity of nonmetals increases going up the periodic table, oxygen is therefore the most reactive nonmetal in the group. So, the answer is oxygen
They are both physical changes (change in physical structure/appearance)
hope this helps :)
