Answer:
We do something called hypothesis
Answer:
1. Make an observation.
2. Ask a question.
3. Propose a hypothesis.
4. Make predictions.
5. Test the predictions.
6. Iterate.
and if it can't be trsted the you did something wrong
Explanation:
The scientific method
At the core of biology and other sciences lies a problem-solving approach called the scientific method. The scientific method has five basic steps, plus one feedback step:
Make an observation.
Ask a question.
Form a hypothesis, or testable explanation.
Make a prediction based on the hypothesis.
Test the prediction.
Iterate: use the results to make new hypotheses or predictions.
The scientific method is used in all sciences—including chemistry, physics, geology, and psychology. The scientists in these fields ask different questions and perform different tests. However, they use the same core approach to find answers that are logical and supported by evidence.
Scientific method example: Failure to toast
Let's build some intuition for the scientific method by applying its steps to a practical problem from everyday life.
What should you do every time you are about to heat glassware on a hot plate?
Select one or more:
Check that there are no cracks in the glassware
Ensure that the glassware is designed for heating
Inspect the hot plate for frayed cords
0 Measure the height and width of the glassware
Answer:
Ensure that the glassware is designed for heating
Check that there are no cracks in the glassware
Inspect the hot plate for frayed cords
Explanation:
All except measuring the height and width of the glassware could cause hazards within the lab.
Which of the following statements about 13C NMR is not true?A. In 13C proton-decoupled NMR spectra, all peaks are singlets.B. 13C NMR spectra display peaks for only carbons that bear hydrogen atoms.C. 13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts.D. 13C NMR easily differentiates between the different hybridized carbons (sp3, sp2, and sp hybridized carbons).organic-chemistry
Answer: .B. 13C NMR spectra display peaks for only carbons that bear hydrogen atoms.
Explanation:
The statements that are true about 13C NMR are:
A. In 13C proton-decoupled NMR spectra, all peaks are singlets.
C 13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts.
D. 13C NMR easily differentiates between the different hybridized carbons (sp3, sp2, and sp hybridized carbons).organic-chemistry
Therefore, the option that isn't true is option B. "13C NMR spectra display peaks for only carbons that bear hydrogen atoms". This is false because 13C NMR will show every peak in the spectrum and it doesn't matter if it's only carbons that bear hydrogen atoms as everything will be shown.
1)
Which of the following would a chemist be most likely to study?
A what happens when a moving car comes to a stop
B.
what happens when iron rusts in the presence of water
C. what happens when ice melts to form liquid water
D. what happens when light reflects from a shiny surface
Answer:
B. what happens when iron rusts in the presence of water
Explanation:
Chemistry is a branch of science involving the composition and changes of matter. In other words, a chemist, who is a trained specialist in the science of chemistry, seeks to answer questions related to properties of matter.
In this question, a chemist is most likely to study "what happens when iron rusts in the presence of water" because it involves a change in the chemical properties of a substance (iron) i.e. a chemical change. However, what happens when ice melts to liquid water is a physical change.
4. A solution contains 62.1 g of ethylene glycol dissolved in 250.0 g of H2O. Calculate the mass % of ethylene glycol
Answer:
Explanation:
% mass of Ethylene glycol =( mass of ethylene glycol/ mass of solution )x100%
= 62.1 g/ (62.1 + 250 ) x 100%
= 24.24%
Mass percentage is a term that represents the concentration, basically mass by mass percentage. It tells about the percentage of a component in a whole component. Therefore, the mass % of ethylene glycol is 24.24%.
What is percentage by mass?Mass percentage represents the the percentage of each element that is making a particular compound. Mass percentage does not have any unit as numerator and denominator contains the same unit.
Mathematically,
Percentage of mass = (component’s mass ÷ total mass) x 100%
% mass of Ethylene glycol =( mass of ethylene glycol/ mass of solution)x100%
% mass of Ethylene glycol = 62.1 g/ (62.1 + 250 ) x 100
= 24.24%
Therefore, the mass % of ethylene glycol is 24.24%.
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What is the symbol for the element that has 12 protons,14 neutrons, and 12 electrons
Answer:
mg
Explanation:
why do NH3 and SO3 have different bond angles, even though they have the same number of atoms?
Answer:
Due to different atoms and different values of electronegativities.
Explanation:
NH3 and SO3 have different bond angles because both molecules have different type of atoms combine together. In NH3, nitrogen react with hydrogen while in SO3, sulfur react with oxygen atom. The bond angle of NH3 is 107 while the bond angle of SO3 is 120. This difference in bond angle is also due to different electronegativities of the bonded atoms. The electronegativity of oxygen is higher than hydrogen so repulsion of hydrogen is less and that's why its bond angle is also lower than oxygen.
Using the brønsted theory, classify the compounds as either an acid or a base
1. HCOO-
2. HNO3
3. -CH3COOCH3
4. HCOOH
Answer:
all the below are ACIDS
Explanation:
1.HCOO- Formate
HCOO- is a conjugate base.
2.HNO3- Nitric Acid
Acid
3.CH3COOCH3: Methyl acetate
Acid
4. HCOOH: Formic Acid
Acid
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2. Jacy bought a gold necklace weighing 21.3 grams from a flea market She filled a 10ml graduated cylinder with water to the 50 mL mark and dropped her necklace in. The level in the graduated cylinder rose to 7.4mL is her necklace real or fake? If not, identify the possible composition of her necklace
Gold: 19.3 g/cm^3
Copper 8.86 g/cm^3
Bronze: 9.87 g/cm^3
Answer:
The necklace is fake.
The necklace is made up of copper.
Explanation:
The following data were obtained from the question:
Mass of the necklace = 21.3 g
Volume of water = 5 mL
Volume of water + Necklace = 7.4 mL
To identify the composition of the necklace, we shall determine the density of the necklace.
This can be obtained as follow:
We'll begin by calculating the volume of the necklace. This can be obtained as shown below:
Volume of water = 5 mL
Volume of water + Necklace = 7.4 mL
Volume of Necklace =.?
Volume of Necklace = (Volume of water + Necklace) – (Volume of water)
Volume of Necklace = 7.4 – 5
Volume of Necklace = 2.4 mL
NOTE:
1 mL = 1 cm³
Therefore,
Volume of Necklace = 2.4 mL = 2.4 cm³
Finally, we shall determine the density of the necklace as follow:
Mass of the Necklace = 21.3 g
Volume of Necklace = 2.4 cm³
Density of Necklace =?
Density = mass /volume
Density = 21.3 / 2.4
Density = 8.87 g/cm³
Therefore, the density of the necklace is 8.87 g/cm³.
From the question given above, we were told Jacy bought a gold necklace.
But comparing the density of necklace to the densities given above the necklace is obviously made of copper material.
Therefore, Jacy bought a fake gold necklace.
Identify the polyatomic ion and its charge in each compound (a) KNO2 K N O 2 (b) CaSO4 C a S O 4 (c) Mg(NO3)2
Answer:
Explanation:
Polyatomic ions are ions (usually anions) that are made up of more than one atom. In order to determine the charge of anions, one can first identify the charge of the metal (which forms the cation) in a compound (which is usually easy to know) before predicting the charge of the anion. The charges are usually exchanged to form denominator of the other reacting atom/molecule, but if divisible, they are divided first before the exchange.
(a) The polyatomic ion in KNO₂ is NO₂ with the ionic equation below showing it's charge
KNO₂ ⇒ K⁺ + NO₂⁻
From the above, we can deduce that the charge of NO₂ is "1-"
(b) The polyatomic ion in CaSO₄ is SO₄ with the ionic equation below showing it's charge
CaSO₄ ⇒ Ca²⁺ + SO₄²⁻
The charge of SO₄ from the above equation is "2-"
(c) The polyatomic ion in Mg(NO₃)₂ is NO₃ with the ionic equation below showing it's charge
Mg(NO₃)₂ ⇒ Mg²⁺ + NO₃⁻
From the above equation, it can be deduced that the charge of NO₃ is "1-"
(0.0046 x 15000.0) + (2817 x 13)
Answer:
36690
Explanation:
Write 0.00103 in scientific notation
Answer:
1.03
Explanation:
You would take 0.00103 and move the decimal like this; 0001.03, we wouldn't have the zeroes in front of the one, as it can throw us off. Therefore, your answer would be 1.03.
Hope I helped! Don't hesitate to let me know if I made a mistake.
A recipe calls for 12 ounces of cocoa powder. All you have are measuring cups. If cocoa powder weighs 0.652 grams per cm3, how many cups of cocoa powder will you need? (1 Tbsp = 15 mL; 1 cup = 16 Tbsp; 1 mL = 1 cc3; 28.4 g = 1 oz.)
Answer:
1 and a half cups
Explanation:
12 ounces is equivalent to 1.5 cups
A diprotic acid, H₂A, has Ka1 = 3.4 × 10⁻⁴ and Ka2 = 6.7 × 10⁻⁹. What is the pH of a 0.18 M solution of H₂A?
Answer:
pH = 2.10
Explanation:
We name an acid as diprotic because it can release two protons:
H₂A + H₂O ⇄ H₃O⁺ + HA⁻ Ka₁
HA⁻ + H₂O ⇄ H₃O⁺ + A⁻² Ka₂
We propose the mass balance:
Analytical concentration = [H₂A] + [HA⁻] + [A⁻²]
As Ka₂ is so small, we avoid the [A⁻²] so:
0.18 M = [H₂A] + [HA⁻]
But we can not avoid the HA⁻, because the Ka₁. Ka₁'s expression is:
Ka₁ = [H₃O⁺] . [HA⁻] / [H₂A]
We propose the charge balance:
[H₃O⁺] = [HA⁻] + [A⁻²] + [OH⁻]
As we did not consider the A⁻², we can miss the term and if
Kw = H⁺ . OH⁻
We replace Kw/H⁺ = OH⁻. So the new equation is:
[H₃O⁺] = [HA⁻] + Kw / [H₃O⁺]
The acid is so concentrated, so we can avoid the term with the Kw, so:
[H₃O⁺] = [HA⁻]
In the mass balance we would have:
0.18 M = [H₂A]
We replace at Ka₁
Ka₁ = [H₃O⁺] . [HA⁻] / [H₂A]
Ka1 . 0.18 / [H₃O⁺] = [HA⁻]
We replace at the charge balance:
[H₃O⁺] = Ka1 . 0.18 / [H₃O⁺]
[H₃O⁺]² = 3.4×10⁻⁴ . 0.18
[H₃O⁺] = √(3.4×10⁻⁴ . 0.18)
[H₃O⁺] = 7.82×10⁻³
- log [H₃O⁺] = pH → - log 7.82×10⁻³
pH = 2.10
Following are the calculation to the pH:
For First ionization:
[tex][H^+] = (K_{a1} \times C)^{\frac{1}{2}}[/tex]
where
C = initial concentration of acid [tex]= 0.18\ M[/tex]
[tex][H^{+}] = (3.4 \times 10^{-4} \times 0.18 \ M)^{\frac{1}{2}}\\[/tex]
[tex][H^{+}] = 0.007\ M[/tex]
For Second ionization:
[tex][H^{+}] = K_{a2} \\\\[/tex]
[tex][ H^{+} ] = 6.7 \times 10^{-9}\ M \\[/tex]
[tex]Total [H^{+}] = 0.007\ M + 6.7 \times 10^{-9}\ M\\\\Total [H^{+}] = 0.007 \ M[/tex]
[tex]pH = -\log[H^+] \\\\pH = -\log(0.007 \ M)\\\\pH = 2.15[/tex]
Therefore, the pH is "2.15".
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The MSDS for benzene indicates that it is a clear liquid that has a substantial vapor pressure. It has a health rating of
2, a fire rating of 3, and a reactivity rating of O. It is a cancer-causing agent.
Based on this information, which statement about benzene is accurate?
O Benzene readily reacts with moist air.
O Benzene explodes if the container is shaken.
O Benzene must be kept away from flames.
O Benzene must be stored under high pressure.
Answer:
Benzene must be kept away from flames.
Explanation:
Hello,
In this case since MSDS tables show the potential risks of chemical compounds, for benzene which which has a substantial vapor pressure and a fire rating of 3, which means that is highly flammable (very likely to get on fire), we conclude then that benzene must be kept away from flames due to its high risk. The other options are incorrect since it has 0 reactivity, it is nor fragile so it is not affected by shaking and it could be storage at standard pressures since it is a liquid at standard conditions as well.
Regards.
How many m^3 are in 56cm^3?
Answer:
5.6 × 10-5 m^3
Explanation:
Hope this helps
To create increased pressure in the lungs which of the following muscles might be active? Mark all that apply. (A) External Intercostals (B) Internal Intercostals (C)Pectoralis major (D) Abdominal muscles (E) Diaphragm (F) Serratus anterior
Answer:
the diaphragm,the rib cage muscles and the abdominal muscles.
Explanation:
From a functional point of view, there are three groups of respiratory muscles: the diaphragm, the rib cage muscles and the abdominal muscles. Each group acts on the chest wall and its compartments, i.e. the lung-apposed rib cage, the diaphragm-apposed rib cage and the abdomen.
An element has a mass number of 9 and 5 neutrons. What element is it?
Answer:
Fluorine
Fluorine is the element in question, as its atomic number is 9 . You would name this particular isotope using the mass number. It would be called fluorine-19.
Explanation:
Answer:
Fluorine
Fluorine is the element in question, as its atomic number is 9 . You would name this particular isotope using the mass number. It would be called fluorine-19.
If your front lawn is 25.0 feet wide and 20.0 feet long, and each square foot of lawn accumulates 1350 new snowflakes every minute, how much snow, in kilograms, accumulates on your lawn per hour? Assume an average snowflake has a mass of 1.90 mg.
Answer:
19.17 kgExplanation:
calculate area of lawn
25 * 20 = 500 sq ft
calculate how many flakes fall per minute
500 * 1150 = 575 , 000 flakes/minute
convert per minute rate to per hour rate
575 , 000 * 60 = 34 ,500 , 000 flakes/hour
now you know how many flakes feel in that one hour so we can now weigh them
34 , 500 , 000 / 1.8 = 19 , 166 , 667 mg (rounded)
convert to kilograms
19 , 166 , 667 / 100 , 000 = 19.17 kg (rounded)
The sense of hotness or coldness by touching always does not work well.why?
Answer:
because if the hotness should more it will give it increase the temperature of earn water but it is not so because you have taken out hands from your and cold water So it is reliable
From the following list of elements, select the elements that are likely to form a cation. Choose one or more: A. oxygen B. chlorine C. calcium D. barium E. cesium F. rubidium G. lead H. scandium I. phosphorous From the following list of elements, select those that will always form ionic compounds in a 1:2 ratio with the halogens. Choose one or more: A. phosphorous B. lead C. chlorine D. cesium E. rubidium F. scandium G. barium H. oxygen I. calcium
Answer:
(i). The elements that are likely to form a cation
(C). calcium, (D). barium, (E). cesium, (F). rubidium, (G). lead and (H). scandium
(ii). The elements those that will always form ionic compounds in a 1:2 ratio with the halogens
(B). lead, (G) barium and (I). calcium
Explanation:
Given that,
The following list of elements,
A. oxygen B. chlorine C. calcium D. barium E. cesium F. rubidium G. lead H. scandium I. phosphorous
We know that,
Cation is defined as, an element which is able to donate electron easily and obtained positive ion.
All metal elements able to form cations.
We need to find the elements that are likely to form a cation
Using given list
(C). calcium
(D). barium
(E). cesium
(F). rubidium
(G). lead
(H). scandium
(II). The following list of elements,
A. phosphorous B. lead C. chlorine D. cesium E. rubidium F. scandium G. barium H. oxygen I. calcium
We know that,
All given metal ions can form ionic compound with halogens as 1:2 ratio because all given metals can form +2 charge.
We need to calculate the elements those that will always form ionic compounds in a 1:2 ratio with the halogens
Using given list.
(B). lead
(G) barium
(I). calcium
Hence, (i). The elements that are likely to form a cation
(C). calcium, (D). barium, (E). cesium, (F). rubidium, (G). lead and (H). scandium
(ii). The elements those that will always form ionic compounds in a 1:2 ratio with the halogens
(B). lead, (G) barium and (I). calcium
I have a buddy who recycles electronics, and isolates metals from the connector pins electrical boards. He isolates gold, for example, and purifies it the best he can, then sells it along with his other scrap metal. This last go around he was able to isolate 3.00 g of Au with a process he claims results in a 80.0% yield. If he is correct, what was his theoretical yield
Answer:
Theoretical yield = 3.75g
Explanation:
Percent yield is defined as one hundred times the ratio between actual yield and theoretical yield. The expression is:
Percent yield = Actual Yield / Theoretical Yield * 100
In the problem, your actual yield was 3-00g.
Percent yield is 80.0%.
Solving for theoretical yield:
80% = 3.00g / Theoretical yield * 100
Theoretical yield = 3.00g / 80.0% * 100
Theoretical yield = 3.75gTo obtain the number of meters from a distance measured in centimeters, you must
By the number
Answer:
Divide by 100
Explanation:
Chlorine could combine with _ to gain the extra electron it needs to stabilize its outer shell
outer shell.
A. helium
B. sulfur
C. hydrogen
D. none of these
Answer:
C, hydrogen.
Explanation:
10. If you were running an experiment to determine the temperature at
which beans sprout the fastest, what would be the independent variable?
A.The number of beans you plant.
B.The height of the sprouts you grow
C.The amount of water you give the beans.
D. The temperature at which each bean is kept.
.
Answer:
The temperature at which each bean is kept
Explanation:
Independent variable is what YOU CHANGE
The temperature at which each bean is kept is the independent variable.
INDEPENDENT VARIABLE:
Independent variable is a variable that is changed or manipulated by the experimenter. The independent variable, which is also called manipulable variable, causes the dependent variable to respond, which is measured or recorded. In an experiment to determine the temperature at which beans sprout the fastest, the independent variable is the temperature at which each bean is kept is the independent variable.Learn more: https://brainly.com/question/17498238?referrer=searchResults
Zirconium dioxide (ZrO2), sometimes known as zirconia, is a white crystalline oxide of zirconium. It can be used in oxygen sensors and fuel cell membranes because it has the ability to allow oxygen ions to move freely through the crystal structure at high temperatures. The ionic radius of Zr is 0.079 nm, and the ionic radius of Cl is 0.140 nm. What is the coordination number of ZrO2?a. 3b. 6c. 4
Answer:
The coordination number of ZrO₂ = 6
Explanation:
A crystal structure is determined by the ratio of ionic radii of the positive and negative ions present in the crystal.
The ratio of the radii of the positive(cations) and negative(anions) is called the limiting radius ratio and it gives the coordination number of the crystal.
Limiting radius ratio = radius of cation/radius of anion
For ZrO₂:
radius of Zr ion (Zr⁴⁺) = 0.079 nm; radius of O ion (O²⁻) = 0.140 nm
Limiting radius ratio = 0.079 nm/0.140 nm = 0.564
From tables, when the limiting radius ratio value is between 0.414 - 0.732, the coordination number is six and the shape of the crystal is octahedral.
Therefore, the coordination number of ZrO₂ = 6
Calculate the mass (in grams) of 0.473 mol of titanium
Explanation:
n=given mass ÷molar mass
make given mass become the subject of the formula by
multiplying the molar mass on both sides of the equation.
n=0.473mol
given mass=??
molar mass=48
therefore,given mass=n×molar mass
=0.473×48
=22.704grams
mass in grams is 22.704grams
The mass (in grams) of 0.473 mol of titanium is 22.6 grams.
We have some specific amount of moles of titanium.
We have to calculate the mass of given sample of titanium.
What is Titanium ?Titanium is a chemical element with the symbol Ti and atomic number 22. It is found in nature only as an oxide.
According to the question -
Moles of titanium - 0.473 moles.
Mass of 0.473 moles of titanium =
0.473 moles titanium x (47.87 grams titanium / 1 mole) = 22.6 grams
Hence, the mass (in grams) of 0.473 mol of titanium is 22.6 grams.
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You should run as an experiment several times to make sure your results are consistent. in the preceding phrase , what does consistent mean
Answer:
To get a final result of experiments, an experiment is repeated several times and the result is noted every time to make sure the results are consistent.
Here the "consistent" meaning is either "same" or "nearby". Consistent results are required in experiments that show constant relation of an experiment to the same principles and the result is not different when performed the same experiment several times.
When performing the same experiment several times, the end result of each experiment should consistent means adhered to the same principle for a successful experiment.
Determine the pH of 023M HNO3 solution.
Answer:
pH = 1.683
Explanation:
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A solid keeps its shape due to which of the following factors? (3 points)
а
Space between particles
Attractive forces between particles
b
Ос
The type of element in the solid
Od
The container it is placed in
Answer: Attractive forces between particels
Explanation:
Which of the following represents the least number of molecules?
(a) 20.0 g of H2O (18.02 g/mol)
(b) 77.0 g of CH4 (16.06 g/mol)
(c) 68.0 g of CaH2 (42.09 g/mol)
(d) 100.0 g of N2O (44.02 g/mol)
(e) 84.0 g of HF (20.01 g/mol)
Answer:
A ; 20g of water has the least number of molecules
Explanation:
Here, we want to know which of the options represent the least number of molecules;
To calculate this, we are going to first calculate the number of moles using the formula below;
Number of moles = mass/molar mass
Then from the number of moles, we can calculate the number of molecules by multiplying the number of moles by 6.02 * 10^23 molecules
Let’s proceed;
a. That will be 20/18.02 = 1.1099 moles
1.1099 * 6.02 * 10^23 = 6.68 * 10^23 molecules
b. That will be 77/16.06 = 4.8 moles
4.8 * 6.02 * 10^23 = 2.89 * 10*24 molecules
c. That will be 68/42.09 = 1.62 moles
1.62 * 6.02 * 10^23 = 9.73 * 10^23 molecules
d. That will be 100/44.02 = 2.27 moles
2.27 * 6.02 * 10^23 = 1.37 * 10^24 molecules
e. That will be = 84/20.01 = 4.2 moles
4.2 * 6.02 * 10^23 = 2.53 * 10^24 molecules
From all the values obtained, the lowest is 20g of water