Answer:this case, the mass is 2.0g, the specific heat capacity of water is 4.18J/g/K, and the change in temperature is 5.0°C=5K , therefore the energy needed to raise it is: 5×2×4.18=41.8J
Explanation:
Answer:
t = 55.79 min
Explanation:
First, the problem is asking for calculate the time that it takes electrons from the battery to the motor.
The general formula to calculate time is:
<em>t = d/V (1)</em>
Where:
d: distance or length
V: speed
Now, we don't have data of speed, but we can know an expression of current density in function of the distance which is the following:
<em>J = n*q*V (2)</em>
Where:
q: charge of the particle (1.6x10^-19 C)
n: number of charge carriers per unit of volume
Current density (J) is actually current per Area so:
<em>J = I/A (3)</em>
Replacing (3) in (2) we have:
I/A = nqV
Solving for V:
<em>V = I/Anq (4)</em>
Finally, if we replace this expression in (1) we have:
<em>t = nqAd / I (5)</em>
Now, the value of n, it's not given but it can be calculated because we have mass density, molar mass and avogadro's number, so this value of "n" can be calculated using the following expression:
<em>n = D * Av / MM (6)</em>
Where:
D: mass density (kg/m³)
Av: avogadro number (6.02x10^23 atom/mol)
MM: molar mass (kg/mol)
Putting the data that we know to calculate n we have:
n = 8960 * 6.02x10^23 / 0.0635
n = 8.49x10^28 atom/m³
Now with the value of n, we can finally calculate the time:
<em>t = nqAd / I </em>
A is the area and it should be in m²: 44.6 mm² / 1x10^6 m = 4.46x10^-5 m²
d is the length in meter: 75.7 cm / 100 cm/m = 0.757 m
so replacing these data in (5):
t = 8.49x10^28 * 1.6x10^-19 * 4.46x10^-5 * 0.757 / 137
t = 3,347.63 s
But the answer is in minute so:
t = 3,347.63 / 60
<em>t = 55.79 min</em>
so the electrons takes 56 min aprox. to go from the car battery to the starting motor.
Answer:
Molar mass of unknown solute is 679 g/mol
Explanation:
Let us assume that the solute is a non-electrolyte.
For a solution with non-electrolyte solute remains dissolved in it -
Depression in freezing point of solution, 
where, m is molality of solute in solution and 
is cryogenoscopic constant of solvent.
Here 
If molar mass of unknown solute is M g/mol then-
So, 
so, M = 679 g/mol
Answer:
Percent error = 25%
Explanation:
Given data:
Measured density of water = 1.25 g/mL
Accepted density value of water = 1 g/mL
Percent error = ?
Solution:
Formula:
Percent error = (measured value - accepted value / accepted value) × 100
Now we will put the values in formula:
Percent error = (1.25 g/mL - 1 g/mL /1 g/mL )× 100
Percent error = (0.25 g/mL /1 g/mL )× 100
Percent error = 0.25 × 100
Percent error = 25%
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>
