Answer:
1
Explanation:
outershell atoms of an element are also known as valency of that element
so the valency and number of elctron in the outershell of a sodium atom is +1.
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Answer:
Explanation:
Hello,
Considering the ideal equation of state:
The moles are defined in terms of mass as follows:
Whereas 
the gas' molar mass, thus:
Now, since the density is defined as the quotient between the mass and the volume, we get:
Solving for 
:
Thus, the result is given by:
![density=\frac{(1atm)(44g/mol)}{[0.082atm*L/(mol*K)]*298.15K} \\density=1.8g/L=1.8x10^{-3}g/mL](https://tex.z-dn.net/?f=density%3D%5Cfrac%7B%281atm%29%2844g%2Fmol%29%7D%7B%5B0.082atm%2AL%2F%28mol%2AK%29%5D%2A298.15K%7D%20%5C%5Cdensity%3D1.8g%2FL%3D1.8x10%5E%7B-3%7Dg%2FmL)
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Answer:
9.34x10^-4
Explanation:
Step 1:
The balanced equation for the reaction.
PbCl2( s ) <=> Pb^2+(aq) + 2Cl^−(aq)
Step 2:
Data obtained from the question:
Mass of PbCl2 = 0.2393 g
Volume = 50mL
concentration of Pb^2+, [Pb^2+] = 0.0159 M
Concentration of Cl^-, [Cl^-] = 0.0318 M
Equilibrium constant, Kc =?
Step 3:
Determination of the number of mole PbCl2.
The number of mole of PbCl2 can be obtained as follow:
Molar Mass of PbCl2 = 207 + (35.5x2) = 278g/mol
Mass of PbCl2 = 0.2393 g
Number of mole =Mass /Molar Mass
Number of mole of PbCl2 = 0.2393/278 = 8.61x10^-4 mole
Step 4:
Determination of Molarity of PbCl2.
At this stage we shall obtain the molarity of PbCl2. This is shown below:
Mole of PbCl2 = 8.61x10^-4 mole
Volume = 50mL = 50/1000 = 0.05L
Molarity of PbCl2 =?
Molarity = mole /Volume
Molarity of PbCl2 = 8.61x10^-4/0.05
Molarity of PbCl2 = 0.01722 M
Step 5:
Determination of the equilibrium constant Kc.
PbCl2( s ) <=> Pb^2+(aq) + 2Cl^−(aq)
The equilibrium constant Kc for the equation above is given by:
Kc = [Pb^2+] [Cl^-]^2 / [PbCl2]
[Pb^2+] = 0.0159 M
[Cl^-] = 0.0318 M
[PbCl2] = 0.01722 M
Kc =?
Kc = [Pb^2+] [Cl^-]^2 / [PbCl2]
Kc = 0.0159 x (0.0318)^2/ 0.01722
Kc = 9.34x10^-4
1. Always give your graph a title in the following form: "The dependence of (your dependent variable) on (your independent variable). <span><span>Let's say that you're doing a graph where you're studying the effect of temperature on the speed of a reaction. In this reaction, you're changing the temperature to known values, so the temperature is your independent variable. Because you don't know the speed of the reaction and speed depends on the temperature, the speed of the reaction is your dependent variable. As a result, the title of your graph will be "The dependence of reaction rate on temperature", or something like that.</span>
</span>2. The x-axis of a graph is always your independent variable and the y-axis is the dependent variable.<span>For the graph described above, temperature would be on the x-axis (the one on the bottom of the graph), and the reaction rate would be on the y-axis (the one on the side of the graph)
</span>3. Always label the x and y axes and give units.<span>Putting numbers on the x and y-axes is something that everybody always remembers to do (after all, how could you graph without showing the numbers?). However, people frequently forget to put a label on the axis that describes what those numbers are, and even more frequently forget to say what those units are. For example, if you're going to do a chart which uses temperature as the independent variable, you should write the word "temperature (degrees Celsius)" on that axis so people know what those numbers stand for. Otherwise, people won't know that you're talking about temperature, and even if they do, they might think you're talking about degrees Fahrenheit.
</span>4. Always make a line graph<span><span>Never, ever make a bar graph when doing science stuff. Bar graphs are good for subjects where you're trying to break down a topic (such as gross national product) into it's parts. When you're doing graphs in science, line graphs are way more handy, because they tell you how one thing changes under the influence of some other variable. </span>
</span><span>5. Never, EVER, connect the dots on your graph!Hey, if you're working with your little sister on one of those placemats at Denny's, you can connect the dots. When you're working in science, you never, ever connect the dots on a graph.Why? When you do an experiment, you always screw something up. Yeah, you. It's probably not a big mistake, and is frequently not something you have a lot of control over. However, when you do an experiment, many little things go wrong, and these little things add up. As a result, experimental data never makes a nice straight line. Instead, it makes a bunch of dots which kind of wiggle around a graph. This is normal, and will not affect your grade unless your teacher is a Nobel prize winner. However, you can't just pretend that your data is perfect, because it's not. Whenever you have the dots moving around a lot, we say that the data is noisy, because the thing you're looking for has a little bit of interference caused by normal experimental error.</span><span>To show that you're a clever young scientist, your best bet is to show that you KNOW your data is sometimes lousy. You do this by making a line (or curve) which seems to follow the data as well as possible, without actually connecting the dots. Doing this shows the trend that the data suggests, without depending too much on the noise. As long as your line (or curve) does a pretty good job of following the data, you should be A-OK.
</span>6. Make sure your data is graphed as large as possible in the space you've been given.<span><span>Let's face it, you don't like looking at little tiny graphs. Your teacher doesn't either. If you make large graphs, you'll find it's easier to see what you're doing, and your teacher will be lots happier.</span>
</span><span>So, those are the steps you need to follow if you're going to make a good graph in your chemistry class. I've included a couple of examples of good and bad graphs below so you know what these things are supposed to look like.</span>
