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MariettaO [177]
3 years ago
12

3. Students measured the mass of the reactants and products for a combustion reaction they observed.

Chemistry
1 answer:
coldgirl [10]3 years ago
4 0

Answer:

A. Students made a measurement error, because ending with more products is impossible.

Explanation:

The law of conversation of matter tells us that in a chemical reaction, matter is never created or destroyed, it's simply converted from one form to another. So the mass of reactants should always equal the mass of the products in a chemical reaction. If there is excess mass in the product, the students have made an error of some kind.

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A buffer solution is made that is 0.347 M in H2C2O4 and 0.347 M KHC2O4.
irga5000 [103]

Answer:

1. pH = 1.23.

2. H_2C_2O_4(aq) +OH^-(aq)\rightarrow HC_2O_4^-(aq)+H_2O(l)

Explanation:

Hello!

1. In this case, for the ionization of H2C2O4, we can write:

H_2C_2O_4\rightleftharpoons HC_2O_4^-+H^+

It means, that if it is forming a buffer solution with its conjugate base in the form of KHC2O4, we can compute the pH based on the Henderson-Hasselbach equation:

pH=pKa+log(\frac{[base]}{[acid]} )

Whereas the pKa is:

pKa=-log(Ka)=-log(5.90x10^{-2})=1.23

The concentration of the base is 0.347 M and the concentration of the acid is 0.347 M as well, as seen on the statement; thus, the pH is:

pH=1.23+log(\frac{0.347M}{0.347M} )\\\\pH=1.23+0\\\\pH=1.23

2. Now, since the addition of KOH directly consumes 0.070 moles of acid, we can compute the remaining moles as follows:

n_{acid}=0.347mol/L*1.00L=0.347mol\\\\n_{acid}^{remaining}=0.347mol-0.070mol=0.277mol

It means that the acid remains in excess yet more base is yielded due to the effect of the OH ions provided by the KOH; therefore, the undergone chemical reaction is:

H_2C_2O_4(aq) +OH^-(aq)\rightarrow HC_2O_4^-(aq)+H_2O(l)

Which is also shown in net ionic notation.

Best regards!

4 0
3 years ago
hat is the percentage of water in the following compound? Answer using three significant figures. Sodium carbonate decahydrate,
BigorU [14]
You need to find the whole molar mass of the compound using the periodic table to add the values. 

Na2CO3= (2 x 23.0) + 12.0 + (3 x 16.0)= 106 g/mol
H2O= 10 x [ (2 x 1.01 ) + (16.0) ]= 180.2 g/mol

the total molar mass is 106 + 180.2 = 286.2 g/mol

the percentage of water you can find by doing "parts over the whole"

H2O%= 180.2 / 286.2 X 100= 63.0%
7 0
3 years ago
Modern oil tankers weigh over a half-million tons and have lengths of up to one-fourth miles. Such massive ships require a dista
uranmaximum [27]

Answer:

Acceleration = (change in speed) / (time for the change)

Change in speed= (0 - 26 km/hr) = -26 km/hr

(-26 km/hr) x (1,000 m/km) x (1 hr / 3,600 sec) = -7.222 m/sec

Average acceleration = (-7.222 m/s) / (22 min x 60sec/min) = -0.00547 m/sec²

Average speed during the stopping maneuver =

              (1/2) (start speed + end speed) = 13 km/hr = 3.6111 m/sec

Explanation:

4 0
3 years ago
This is the measure of the quantity of matter
Akimi4 [234]

Answer : Mass

Explanation : Mass measures the amount of matter in a substance or an object.

3 0
3 years ago
Read 2 more answers
The sink-float method is often used to identify the type of glass material found at crime scenes by determining its density.
Olegator [25]

Answer:

<em><u>Glass that will sink</u></em>

  • alkali zinc borosilicate with a density of 2.57 g/mL in a solution with a density of 2.46 g/mL

  • potash soda lead with a density of 3.05 g/mL in a solution with a density of 1.65 g/mL

<em><u>Glass that will float</u></em>

  • soda borosilicate with a density of 2.27 g/mL in a solution with a density of 2.62 g/mL

  • alkali strontium with a density of 2.26 g/mL in a solution with a density of 2.34 g/mL

<em><u>Glass that will not sink or float</u></em>

  • potash borosilicate with a density of 2.16 g/mL in a solution with a density of 2.16 g/mL

Explanation:

Density is the property of matter that states the ratio of the amount of matter, its mass, to the space occupied by it, its volume.

So, the mathematical expression for the density is:

  • density = mass / volume

By comparing the density of a material with the density of a liquid, you will be able to determine whether object will float, sink, or do neither when immersed in the liquid.

The greater the density of an object the more it will try to sink in the liquid.

As you must have experienced many times an inflatable ball (whose density is very low) will float in water, but a stone (whose denisty is greater) will sink in water.

The flotation condition may be summarized by:

  • When the density of the object < density of the liquid, the object will float
  • When the density of the object = density of the liquid: the object will neither float nor sink
  • When the density of the object > density of the liquid: the object will sink.

<em><u>Glass that will sink</u></em>

  • alkali zinc borosilicate with a density of 2.57 g/mL in a solution with a density of 2.46 g/mL, because 2.57 > 2.46.

  • potash soda lead with a density of 3.05 g/mL in a solution with a density of 1.65 g/mL, because 3.05 > 1.65.

<u><em>Glass that will float</em></u>

  • soda borosilicate with a density of 2.27 g/mL in a solution with a density of 2.62 g/mL, because 2.27 < 2.62.

  • alkali strontium with a density of 2.26 g/mL in a solution with a density of 2.34 g/mL, because 2.26 < 2.34.

<em><u>Glass that will not sink or float</u></em>

  • potash borosilicate with a density of 2.16 g/mL in a solution with a density of 2.16 g/mL, because 2.16 = 2.16
8 0
4 years ago
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