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ZanzabumX [31]
3 years ago
11

Help me pleaseeeeeee

Chemistry
1 answer:
Paha777 [63]3 years ago
7 0
The third one because temperature is being used, so a meter stick wouldn’t make sense. You aren’t measuring the length of anything physically. A stopwatch measures time, which is what they are showing in the chart, so the third one is the only one that makes sense.
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9. Gasoline burns easily if ignited
Elena L [17]

Answer:

I think it is chemical change

5 0
3 years ago
A chemist adds of a iron(III) bromide solution to a reaction flask. Calculate the mass in kilograms of iron(III) bromide the che
vaieri [72.5K]

Answer:

0.246 kg

Explanation:

There is some info missing. I think this is the original question.

<em>A chemist adds 370.0mL of a 2.25 M iron(III) bromide (FeBr₃) solution to a reaction flask. Calculate the mass in kilograms of iron(III) bromide the chemist has added to the flask. Be sure your answer has the correct number of significant digits.</em>

<em />

We have 370.0 mL of 2.25 M iron(III) bromide (FeBr₃) solution. The moles of FeBr₃ are:

0.3700 L × 2.25 mol/L = 0.833 mol

The molar mass of iron(III) bromide is 295.56 g/mol. The mass corresponding to 0.833 moles is:

0.833 mol × 295.56 g/mol = 246 g

1 kilogram is equal to 1000 grams. Then,

246 g × (1 kg/1000 g) = 0.246 kg

3 0
4 years ago
What do we mean when we say a chemical reaction is balanced? (Several choices can be correct.)
Rina8888 [55]

Answer:

2 and 3

Explanation:

A chemical reaction is defined as the process in which two or more reactants combined together chemically and gives a different product.

A balanced chemical equation involves an equal number of atoms on the reactant and product side. A balanced chemical reaction occurs when the atoms present on the reactant side or left side of the arrow is equal to the atoms on the product side or right side of the arrow.

The process of the balanced chemical equation is based on errors and trials in which the atoms in each element is identified, the atoms are then multiplied with required numbers, the addition of coefficient in front of molecules and check the equation at last.

Hence, the correct options are "2 and 3".

3 0
3 years ago
Calculate the pH during the titration of 20.00 mL of 0.1000 M HNO2(aq) with 0.1000 M KOH(aq) after 13.27 mL of the base have bee
Slav-nsk [51]

Answer:

pH = 2.462.

Explanation:

Hello there!

In this case, according to the reaction between nitrous acid and potassium hydroxide:

HNO_2+KOH\rightarrow KNO_2+H_2O

It is possible to compute the moles of each reactant given their concentrations and volumes:

n_{HNO_2}=0.02000L*0.1000mol/L=2.000x10^{-3}mol\\\\n_{KOH}=0.1000mol/L*0.01327L=1.327x10^{-3}mol

Thus, the resulting moles of nitrous acid after the reaction are:

n_{HNO_2}=2.000x10^{-3}mol-1.327x10^{-3}mol=6.73x10^{-4}mol

So the resulting concentration considering the final volume (20.00mL+13.27mL) is:

[HNO_2]=\frac{6.73x10^{-4}mol}{0.01327L+0.02000L} =0.02023M

In such a way, we can write the ionization of this weak acid to obtain:

HNO_2+H_2O\rightleftharpoons NO_2^-+H_3O^+

So we can set up its equilibrium expression to obtain x as the concentration of H3O+:

Ka=\frac{[NO_2^-][H_3O^+]}{[HNO_2]}\\\\7.1x10^{-4}=\frac{x^2}{0.02023M-x}

Next, by solving for the two roots of x, we get:

x_1=-0.004161M\\\\x_2=0.003451M

Whereas the correct value is 0.003451 M. Finally, we compute the resulting pH:

pH=-log(0.003451)\\\\pH=2.462

Best regards!

4 0
3 years ago
Two reasons why scientists create models to study atoms
zaharov [31]
Models are used to study atoms because we can't exactly study an atom with the naked eye, Using an enlarged model of an atom easier to study because we can pin point the different characteristics of the atom.
6 0
3 years ago
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