Nitrogen has 5 valence electrons (ve-), so a diatomic nitrogen molecule will have twice as many, 10 valence electrons. Then, just draw electrons in pairs of 2 until you both get ride of all of them (reach 0) and you fill every atom (eight electrons each). It can be drawn either way, the important thing is that there are 3 electron pairs shared between the two atoms.
This lesson is the first in a three-part series that addresses a concept that is central to the understanding of the water cycle—that water is able to take many forms but is still water. This series of lessons is designed to prepare students to understand that most substances may exist as solids, liquids, or gases depending on the temperature, pressure, and nature of that substance. This knowledge is critical to understanding that water in our world is constantly cycling as a solid, liquid, or gas.
In these lessons, students will observe, measure, and describe water as it changes state. It is important to note that students at this level "...should become familiar with the freezing of water and melting of ice (with no change in weight), the disappearance of wetness into the air, and the appearance of water on cold surfaces. Evaporation and condensation will mean nothing different from disappearance and appearance, perhaps for several years, until students begin to understand that the evaporated water is still present in the form of invisibly small molecules." (Benchmarks for Science Literacy<span>, </span>pp. 66-67.)
In this lesson, students explore how water can change from a solid to a liquid and then back again.
<span>In </span>Water 2: Disappearing Water, students will focus on the concept that water can go back and forth from one form to another and the amount of water will remain the same.
Water 3: Melting and Freezing<span> allows students to investigate what happens to the amount of different substances as they change from a solid to a liquid or a liquid to a solid.</span>
Answer:
The reaction is exothermic.
Yes, released.
The heat released is 4,08x10³ kJ.
Explanation:
For the reaction:
C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l)
The ΔH is -2220 kJ, As ΔH is <0, <em>The reaction is exothermic.</em>
As the reaction is exothermic, the heat of the reaction will be <em>released.</em>
The heat released in 81,0g is:
81,0g C₃H₈×
×
= <em>4,08x10³ kJ</em>
<em>-Using molar mass of C₃H₈ to convert mass to moles and knowing that there are released 2220 kJ per mole of C₃H₈-</em>
I hope it helps!
Answer:
30 moles
Explanation:
Water is H2O, meaning there is 2 Hydrogen atoms and 1 Oxygen atom. Oxygen is O2, because it is a diatomic molecule. (Hydrogen is also a diatomic molecule, so H2)
The equation, balanced, would have to be: 2H2 + O2 -----> 2H2O
I multiply 15 moles O2 by the molar ratio of (hydrogen/oxygen)
15 mol. O2 * (2 mol. H2/1 mol O2) = 30 moles of water
The answer is D, because "Animals without a backbone are invertebrates."
