A 0.500-g sample containing Na2CO3 plus inert matter is analyzed by adding 50.0 mL of 0.100 M HCl, a slight excess, boiling to remove CO2, and then back-titrating the excess acid with 0.100 M NaOH. If 5.6 mL NaOH is required for the back-titration, what is the percent Na2CO3 in the sample?
The percentage by mass of Na2CO3 in the sample is 48%.
The equation of the reaction of Na2CO3 with HCl;
Na2CO3(aq) + 2HCl(aq) ------> 2NaCl(aq) + H2O(l) + CO2(g)
Since the HCl is in excess, the excess is back titrated with NaOH as follows;
NaOH (aq) + HCl(aq) ---->NaCl(aq) + H2O(l)
Number of moles of HCl added = 0.100 M × 50/1000 L = 0.005 moles
Number of moles of NaOH added = 5.6/1000 × 0.100 M = 0.00056 moles
Since the reaction of NaOH and NaOH is 1:1, 0.00056 moles of HCl reacted with excess HCl.
Amount of HCl that reacted with Na2CO3 = 0.005 moles - 0.00056 moles = 0.0044 moles
Now;
1 mole of Na2CO3 reacts with 2 moles of HCl
x moles of Na2CO3 reacts with 0.0044 moles of HCl
x = 1 mole × 0.0044 moles / 2 moles
x = 0.0022 moles
Mass of Na2CO3 reacted = 0.0022 moles × 106 g/mol = 0.24 g
Percentage of Na2CO3 in the sample = 0.24 g/ 0.500-g × 100/1 = 48%
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in a test trial, using 6% extra strength bleach at room temperature, 100.0 mL of oxygen gas was produced in 2.03 seconds. Calculate the average reaction rate for the oxygen gas.
The average reaction rate for oxygen gas is 49.26 mL/s
The average reaction rate of a substance refers to the speed at which a reaction occurs and therefore products are formed. In the reaction presented, oxygen gas is the product.
Moreover, the average reaction rate can be expressed in mL per second or mL/s, and the formula to calculate it is:
Product in mL/seconds
Let's calculate the reaction rate:
100 mL/ 2.03 s = 49.26 mL/sLearn more about oxygen in: https://brainly.com/question/1506082
A photon is BEST described as _?
A. A subatomic particle of light
B. A negatively charged subatomic particle
C. A particle larger than an atom
D. A particle inside an atom
The specific heat of water is 4.184 J/gºC. How much energy (in
joules) is required to raise the temperature of 18g of H2O from
283K to 293K?
Explain in terms of chemical reactivity why the elements in group 18 on the modern periodic table were not identified by Mendeleev's at that time
Answer:
elements tend not to react with other elements, there were no oxide compounds for Mendeleev to study. –Group 18 elements are generally unreactive. sodium ion is smaller because the sodium atom lost one electron. –An Na+ ion is smaller because it has one fewer electron shell.
Explanation:
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Also have a great day and good luck in your studies!
convert 3.79 x 10^24 atoms of sodium to grams
mol = 3.79 × 10^24/6.02 × 10^23 = 6.296 mol
mass = 6.296 × 23 = 144.808 grams
what takes place when the pollen grains are transferred to the stigma of the same flower with the help of pollinators
Answer:
self-pollination.
Explanation:
When the pollen of the flower is transferred to the stigma of the same flower, it is called self-pollination. Cross-pollination occurs when pollen is transferred from one flower to another flower on the same plant, or another plant.
Where do you put the value for how many of each atom you need?
Multiple choice
A. Below and before the symbol.
B. Above and after the symbol.
C. Below and after the symbol.
D. Above and before the symbol.
Answer:A
Explanation
:
97.3 FM radio station broadcasts electromagnetic waves at a frequency of 97.3 megahertz (97.6 x 106 Hz). These radio waves travel at a
speed of 3.00 x 108 m/s. What is the wavelength of these radio waves?
*Include your units!
Round your answer to the nearest hundredth (2 decimal places).
The wavelength of the electromagnetic wave at the given frequency is 3.07 meters.
Given the following data:
Frequency =[tex]97.6 \times 10^6\; Hz[/tex]Speed = [tex]3 \times 10^8\;m/s[/tex]To determine the wavelength of the electromagnetic wave at the given frequency:
Mathematically, the wavelength of an electromagnetic wave is calculated by using the formula;
[tex]Wavelength = \frac{Speed }{frequency}[/tex]
Substituting the given parameters into the formula, we have;
[tex]Wavelength = \frac{3 \times 10^8}{97.6\times 10^{6}}[/tex]
Wavelength = 3.07 meters.
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A student is studying the boiling points of six different liquids and finds results with consistently higher boiling points than what research would suggest. Which option describes a likely cause?
Answer:
Large molecules tend to have greater boiling points because the London dispersion forces are stronger within.
Explanation:
Which of the following expresses the value 300,000,000 in correct scientific notation?
Group of answer choices
3 x 108
0.3 x 10-9
3 x 10-8
0.3 x 109
Answer:
3 x 10^8
Explanation:
Electrical bonding refunding quick check!!
A team wants to understand the effects of molecular weight on boiling point. The team has access to five substances with
different molecular weights and the time to measure 50 boiling points. How can the team make the best use of the laboratory
testing time? (1 point)
O by taking 10 measurements of each of the five liquids and using the highest value from each set
O by taking 10 measurements of each of the five liquids and finding an average
O by taking measurements of the liquids one at a time, making sure that the correct results are achieved before
moving on to another liquid
O by taking one measurement of each liquid and then working to improve the least certain liquid in the group
Answer:
1. More data should be collected to get a more reliable average
2. A boiling point at 1.5 atmospheres could be predicted fairly well
3. The actual boiling point is probably between 34 C and 40 C
4. By taking 10 measurements of each of the five liquids and finding an average
5. The thermometer being used might need to be recalibrated
Explanation:
Took the quick check
Consider the reaction where barium sulfate can be prepared from 2.76 mol of sodium sulfate and excess barium acetate. Sodium acetate is the other product
1.write the balanced MOLECULAR reaction.
2.write the balanced total ionic equation.
3.write the balanced net ionic equation.
Answer:
1. Na2SO4(aq)+C4H6BaO4(aq) --> BaSO4(s) + 2C2H3NaO2(aq)
2. 2Na^+1(aq) + SO4^-2(aq) + 4C^+4(aq) + 6H^+1(aq) + Ba^-2(aq) + 4O^-2(aq) --> BaSO4(s) + 2C^-4(aq) + 2H^+1(aq) + 3Na^+1(aq) + 2O^-2(aq)
3. Ba^+2(aq) + SO4^-2(aq) --> BaSO4(s)
Explanation:
17) An ethanol solution has a concentration of 0.500M. What volume in liters of this solution
would contain 8.0 moles of ethanol?
To calculate the Molar Concentration, we will find the molar concentration by dividing the moles by liters of water used in the solution. For example, the acetic acid here is completely dissolved in 1.25 L of water. Then divide 0.1665 moles by 1.25 L to get the molar concentration, which will be 0.1332 M.
Hope It Helpz(◕ᴥ◕)The model below shows the equation that represents how hydrogen and oxygen combine to form water. In this chemical reaction, the reactants
are hydrogen gas and oxygen gas.
2H2 + O2 + 2H2O
True
False
Answer:
true
Explanation:
because they are balance
what is the true of lewis base
Answer: To answer your question of what is true of a lewis base, it is true that a lewis base donates electron pairs.
Explanation: A Lewis base is any substance, such as the OH- ion, that can donate a pair of nonbonding electrons. A Lewis base is therefore an electron-pair donor.
Passive prostheses are:
- self-regulated
- easily corroded
- made of nanotubes
- self-powered
Passive prostheses are self-regulating, as shown in the first answer option.
We can arrive at this answer because:
Passive prostheses are devices used to replace parts of the body that were lost by an incident.These prostheses are very useful to establish balance or the aesthetics of the body, but they have no articulations and no movement mechanism, being static.This limitation allows passive prostheses not to need external regulation and to be self-regulated by fitting the body parts.
You can find more information about articulations and their effects on the link:
https://brainly.com/question/5847359?referrer=searchResults
Answer:
self-powered.
grtdggddgdggrsggrgrgd
Answer:
wut??
Explanation:
What does lowercase v represent in this formula?
Bill sets up an experiment to determine and predict the velocity of a marble at the end of a track. He uses an electronic balance to weigh the marble. He then places the marble at the top of the track and releases it. Artie uses the time it takes the marble to pass through a photogate at the bottom of the track to calculate the velocity of the marble. ill notes that his prediction is significantly higher than his calculated velocity. Which error explains this difference? A) Bill forgot to account for friction. B) Bill forgot to zero the balance and found a weight for the marble that was too low. C) Bill weighed the marble in a weighing dish and failed to account for the mass of the weighing dish. D) Bill didn't position the photogate correctly and got the time required for the top of the marble to pass through, rather than reach the middle.
Answer:
A
Explanation:
USATestPrep
list 2 sources of waste water
Answer:
residential and domestic sources.
Explanation:
Select the correct answer. What does the kinetic theory state about the relationship between the speed and temperature of gas molecules? A. As the temperature increases, the speed of gas molecules remains constant. B. As the temperature increases, the speed of gas molecules decreases. C. As the temperature increases, the speed of gas molecules increases. D. As the speed of gas molecules increases, the temperature becomes constant. E. As the temperature decreases, the speed of gas molecules increases.
Answer:
C. As the temperature increases,the speed of gas molecules increase.
a fisherman in a boat is drinking a of hot coffee. the large lake below his boat is full of cold water. which statement is an accurate comparison of the lake water and the coffee?
Answer:
see below
Explanation:
The lake will have more total thermal energy but the particles in the coffee will be moving faster.
A comparison of hot coffee and cold lake is, the heat from the coffee will be absorbed by the cold lake through convection method of heat transfer.
Conservation of energy
The principle of conservation of energy states that the total energy of an isolated system is always conserved.
Heat lost by the hot coffee = Heat absorbed by the cold lake
Heat transfer processHeat from the coffee will be absorbed by the cold lake through convection method of heat transfer.
Thus, a comparison of hot coffee and cold lake is, the heat from the coffee will be absorbed by the cold lake through convection method of heat transfer.
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K3PO4(aq)+MgCl2(aq)⟶
Answer:
6KCl(aq) + Mg3(PO4)2(s) ... balanced equation
Explanation:
How many grams of CaSO4 form when
50.0 mL of 0.20 M Ca(NO3)2 react with
excess potassium sulfate solution?
Ca(NO3)2 + K2SO4 → CaSO4 + 2KNO3
-
?] g CaSO4
Answer:
1.36g CaSO4 (FIXED THIS)Explanation:
.01 mol CaSO4 is the conversion factor between these values and now you just need to multiply it by the molar mass of .01 x 136.14=1.36g CaSO4
Apologies for having the wrong answer before this, it's been a long day.
Why do scientists use the scientific method?
A. It helps them do research that other scientists can understand.
B. It helps them ask questions that affect as many people as
possible.
C. It helps them make sure a certain question has not been asked
before.
OD. It helps them determine whether an idea is supported by evidence.
Help
Answer:
DExplanation:
It helps determine whether an idea is supported by evidencehope it helps please follow because I don't have any followers I have 0 followersIndustrial chemists have to understand the chemistry of oxides.
For example, silicon dioxide is used in glass making and carbon monoxide is used in the
extraction of iron from iron ore.
(i) Explain how burning carbon in air can lead to the formation of carbon monoxide.
(2)
(ii) Write the balanced equation for the reaction between silicon and oxygen.
(2)
Answer:
carbon monoxide can be formed due to incomplete combustion of carbon due to insufficient oxygen supply
2C+O2___2CO
Si+O2____SiO2
NEED HELP ASAP WILL GIVE BRAINLIEST
Answer:
2.83
Explanation:
Molar concentration (mol/litre) = mass/molar mass × 1000/volume(in ml)
0.849 = mass/60.09 × 1000/55.5
mass = (0.849 × 60.09 × 55.5)/1000
= 2.8314
To 2 decimal places = 2.83
How are prisms and raindrops alike?
They are both transparent.
They both reflect white light.
They are both translucent.
They both refract white light.
they both refract white light.
Answer:
They both reflect white light.
Explanation:
How raindrops and prism are similar?
Raindrops and prisms are similar because they both cause light to bend when it enters a prism or raindrop. When light enters a raindrop it causes the light to bend (refract) and separates the white lights into different wavelengths, allowing us to see the individual colors of the rainbow.
A team of scientists is working to find the boiling point of a liquid at very low pressure. After three trials, the team has an average
of 12.3°C. An additional trial gives a result of 13.1°C. Which statement is a reasonable conclusion that can be drawn from this
result? (1 point)
O The original average should be thrown out because it could not be confirmed by new results.
O More data should be collected because the first three trials appear to be wrong.
O The original average should be used because it came from three results, not just one.
O More data should be collected to get a more reliable average.
Since it is conventional in science to use an average not just a single result, the original average should be used because it came from three results, not just one.
The boiling point refers to the temperature when the pressure of the fluid equals the atmospheric pressure. Hence, boiling occurs at atmospheric pressure.
In scientific experiments, it is common to conduct experiments more than once and obtain an average value for the measurement. In this case, the original average should be used because it came from three results, not just one.
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