Answer:
130g
Explanation:
For every mole of a substance, there is a molar mass that coincides with the masses on the periodic table. For one mole of H2O, you would add the molar masses of the two hydrogen atoms and the oxygen atom to get 18.016g. You would then take this molar mass and multiple it by the amount of moles present (7.4) to get 133.3184g
From here, you would round to the significant figures to get 130g
Calculate the volume of a box which is 125 cm long, 37 cm wide, and 68 cm high. Report your answer with correct significant figures in cubic centimeters. please use significant figures!
Calculate the volume of a box which is 423 cm long, 12 cm wide, and 25 cm high. have significant figures in cubic centimeters.
Suppose you are measuring the mass of a solid sample on a balance using a weigh boat. You record the data in a table. Mass of weigh boat 1.326 g Mass of weigh boat and sample 7.635 g What is the mass of the solid sample?
A graduated cylinder contains 10.00 mL water. A 14.74 g piece of aluminum is added to the water, and the volume rises to 15.46 mL. What is the density of the aluminum?
A 24.5 g sample of solution has a density of 0.768 g/mL. What is the sample volume (in mL)?
Answer:
1. Volume of box is 314500 cm³.
2. Volume of box 126900 cm³.
3. Mass of sample is 6.309 g.
4. Density of aluminum is 2.7 g/mL.
5. Volume of sample is 31.9 mL.
Explanation:
1. Determination of the volume of the box
Length (L) = 125 cm
Width (W) = 37 cm
Height (H) = 68 cm
Volume (V) =?
V = L × W × H
V = 125 × 37 × 68
V = 314500 cm³
2. Determination of the volume of the box
Length (L) = 423 cm
Width (W) = 12 cm
Height (H) = 25 cm
Volume (V) =?
V = L × W × H
V = 423 × 12 × 25
V = 126900 cm³
3. Determination of the mass of the sample.
Mass of weigh boat = 1.326 g
Mass of weigh boat + Sample = 7.635 g Mass of the sample =?
Mass of Sample = (Mass of weigh boat + Sample) – (Mass of weigh boat)
Mass of Sample = 7.635 – 1.326
Mass of Sample = 6.309 g
4. Determination of the density of aluminum.
Volume of water = 10 mL
Mass of aluminum = 14.74 g
Volume of water + aluminum = 15.46 mL
Density of aluminum =?
Next, we shall determine the volume of aluminum. This can be obtained as follow:
Volume of water = 10 mL
Volume of water + aluminum = 15.46 mL
Volume of aluminum =?
Volume of aluminum = (Volume of water + aluminum) – (Volume of water)
Volume of aluminum = 15.46 – 10
Volume of aluminum = 5.46 mL
Finally, we shall determine the density of aluminum. This can be obtained as follow:
Mass of aluminum = 14.74 g
Volume of aluminum = 5.46 mL
Density of aluminum =?
Density = mass / volume
Density of aluminum = 14.74 / 5.46
Density of aluminum = 2.7 g/mL
5. Determination of the volume of sample.
Mass of sample = 24.5 g
Density of sample = 0.768 g/mL.
Volume of sample =?
Density = mass / volume
0.768 = 24.5 / volume of sample
Cross multiply
0.768 × Volume of sample = 24.5
Divide both side by 0.768
Volume of sample = 24.5 / 0.768
Volume of sample = 31.9 mL.
What is the enthalpy for the following reaction? overall: C + 1/2O2→CO
Answer:
ΔH°(f) = -110.5 Kj/mole (exothermic)
Explanation:
C + 1/2O₂ => CO
This is asking for the 'Standard Heat of Formation (ΔH°(f)* for carbon monoxide (CO). Values for many compounds can be found in the appendix of most college general chemistry text books. From Ebbing & Gammon, 11th edition, General Chemistry, Appendix C, page 8A.
*Standard Heat of Formation by definition is the heat gained or lost on formation of a substance (compound) from its basic elements in standard state.
The ΔH°(f) values as indicated are found in the appendix of most college chemistry texts. By choosing any compound, one can determine the standard heat of formation equation for the substance of interest. For example, consider Magnesium Carbonate; MgCO₃(s).The basic standard states of each element is found in the Appendix on Thermodynamic Properties for Substances at 25°C & 1 atm. having ΔH°(f) values = 0.00 Kj/mole. All elements in standard state have a 0 Kj/mol. See appendix and note that under the ΔH°(f) symbol some substances have 0.00 Kj/mol values. The associated element will be in basic standard state,
Standard Heat of Formation Equation for formation of Magnesium Carbonate;
Mg°(s) + C°(gpt)* + 3/2O₂(g) => MgCO₃(s) ; ΔH°(f) = -1111.7 Kj/mole
* gpt => graphite
You are working in the lab and spill some acid on the counter. Because you don't want to get into trouble, you decide to clean it up by yourself. What would be best to reduce the acidity of the spill?
Answer:
By adding baking soda
Explanation:
The best way to reduce the acidity of the spill would be to add some amount of baking soda to the spill and then clean it up with a towel or any other appropriate item.
Baking soda is made up of sodium bicarbonate and has the capacity to react with acid to produce a salt and carbonic acid. The carbonic acid readily decomposes to produce carbon dioxide and water. For example, sodium bicarbonate reacts with hydrochloric acid according to the equation below:
[tex]NaHCO_3 + HCl --> NaCl + H_2CO3[/tex]
[tex]H_2CO_3 --> H_2O + CO_2[/tex]
One would expect the addition of a base to the spilled acid to work in a way as to neutralize the acid but bases are also corrosive and only a stoichiometrically balanced quantity would completely neutralize the acid. Thus, the quantity might not easily be determinable and one can end up doing more harm than good.
Hence, the best option is to add baking soda to the spilled acid to reduce its acidity before cleaning it off.
PLEASE HELPPP!!!!!!!
Scientists observe patterns in matter. They organize matter into groups based on shared physical and chemical properties. Which statement describes a chemical property that many elements might share?
A. bonds easily with oxygen in the air
B. boils between 90°C and 100°C
C. shines when polished
D. floats in water
Answer:
a
Explanation:
bonding is chemical
A chemicals change includes bond making or breaking. The reaction between two atoms or molecules is their chemical property. Thus bonding with oxygen in air is a common chemical property of elements.
What is chemical change?A change in which a substance undergo chemical bond making or breaking and forming new products. Whereas, a physical change does not involve these bond breaking or formation instead a phase change occurs there. Such as conversion of solids to liquids.
All the elements in the periodic table have their characteristic chemical and physical properties. Metallic shining is a physical property of metallic elements and floats in water describes the density of that element which is a physical property.
Similarly, boiling and melting are physical properties and they do not include any bond formation or breaking of the element.
The reaction with oxygen in air called oxidation forming their oxidised product is a chemical change. Thus, option A is correct.
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atomic radius(size)______ from left to right across a period on the periodic table
Answer:
Decreases
Explanation:
23. How many different elements are in the compound sodium carbonate (Na2CO3)? *
a. 1
b. 3
C. 6
d.7
Na, C, and O so the answer is c. 3
Which chemical equation is unbalanced?
A). C+O,, CO,
B). Sr t+ O2 2SFO
C). 6H, + 30, 6H,O
D). H, +H, +O,-→ H,0 + H,O
Answer:
The options in this question are unclear, the clear options are as follows:
A. C + O2 → CO2
B. Sr + O2 → 2SrO
C. 6H2 + 3O2 → 6H2O
D. H2 + H2 + O2 → H2O + H2O
The answer is B
Explanation:
A balanced chemical equation is that equation in which atoms of each elements in the reaction are of equal number on both sides of the equation (product and reactant). To balance a chemical equation, coefficients are used.
In this question, four chemical equations are given as follows:
- C + O2 → CO2
In this equation, atoms of carbon (1) and oxygen (2) are the same on both sides, hence, it is BALANCED.
- Sr + O2 → 2SrO
In this equation, Sr has 1 atom on the reactant side but 2 atoms on the product side. Hence, it is UNBALANCED. The balanced equation will be: 2Sr + O2 → 2SrO
- 6H2 + 3O2 → 6H2O
In this equation, atoms of hydrogen (12) and oxygen (6) are the same on both sides, hence, it is BALANCED.
- H2 + H2 + O2 → H2O + H2O
In this equation, atoms of hydrogen (4) and oxygen (2) are the same on both sides, hence, it is BALANCED.
Cellular respiration is? (Single choice.)
A. a chemical reaction that converts energy from food molecules by way of oxygen into a usable energy called ATP.
B. a chemical reaction that converts carbon dioxide and water into glucose and oxygen.
C. a chemical reaction that converts that occurs only in animals.
D. a chemical reaction that occurs only in plants.
13 Elements within the same main groups (1-8)
The mass of an unidentified rock is 15.5 grams. Students determine the volume of the rock by placing the rock in a cylinder with water. What was the density of the rock that the students should have calculated?
Hint: The graduated cylinder measures volume. Read the difference in water level.
Considering the following polymer size fractions of a given polymer sample:
Fraction Molecular Weight Number of Chains
1 6,500 400
2 10,000 1000
3 1,000,000 8
(a) Calculate the number-average molecular weight of the polymer.
(b) Calculate the weight-average molecular weight of the polymer.
(c) Which average molecular weight did the 8 chains of molecular weight of 1,000,000 most significantly affect? why?
(d) Calculate the polydispersity index(PI = (Mw/Mn) of the polymer
Answer:
Explanation:
From the information given:
Molecular weight Mi Number of chains (Ni) NiMi
400 6500 2600000
1000 10000 10000000
8 1000000 8000000
[tex]\sum_{Ni} = 1408[/tex] [tex]\sum _{NiMi}[/tex] = 20600000
Thus, the average number of molecular weight = [tex]\dfrac{\sum_{NiMi}}{\sum_{Ni} }[/tex]
[tex]= \dfrac{20600000}{1408}[/tex]
= 14630.68
b)
weight-average molecular weight = [tex]\dfrac{\sum _{NiMi^2} }{\sum _{NiMi}}[/tex]
[tex]Ni[/tex] [tex]Mi[/tex] [tex]Mi^2[/tex] [tex]Ni[/tex] [tex]Mi^2[/tex]
400 6500 42.25 × 10⁶ 16.9 × 10⁹
1000 10000 100 × 10⁶ 100 × 10⁹
8 1000000 1 × 10¹² 800 × 10⁹
[tex]\sum _{NiMi^2} = 916.9 \times 10^9[/tex]
weight-average molecular weight [tex]=\dfrac{916.9 \times 10^9 }{20.6 \times 10^6}[/tex]
= 44509.71
c)
The number average molecular weight is most significantly affected. This is because the number average molecular weight value is worth more in comparison to the weight-average molecular weight.
d)
The polydispersity index (PI) = [tex]\dfrac{\overline {M_W}}{\overline {M_n}}[/tex]
[tex]PI = \dfrac{44509.71}{14630.68}[/tex]
PI = 3.04
When 3.00 moles of hydrogen molecules and 1.50 moles of oxygen molecules react, they form 3.00 moles of water
When 3.00 moles of hydrogen molecules and 1.50 moles of oxygen molecules react, they form 3.00 moles of water
according to the reaction below.
2H2+ O2 + 2H2O
How many grams of oxygen were required?
2H, + O2 + 2H2O
How many grams of oxygen were required?
Mass of Oxygen required : 24 grams
Further explanationGiven
3 moles of H
1.5 moles of O
3 moles of H₂O
Required
Mass of O
Solution
Reaction
2H₂ + O₂ ⇒ 2H₂O
Mass of Oxygen for 1.5 moles of O :
= mol x Ar O
= 1.5 moles x 16 g/mol
= 24 grams
PLEASE HELP!! PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP
CHEMJSTRY!! LONE PAIRS WILL GIVE BRAINLIEST IF CORRECT!
Answer:
T
Explanation:
A chemist determines by measurements that .060 moles of nitrogen gas participate in a chemical reaction. Calculate the mass of nitrogen gas that participates. Be sure your answer has the correct number of significant digits.
Answer:
1.7 g N₂
Explanation:
In order to convert moles of nitrogen gas (N₂) to grams, we'll use its molar mass:
Molar mass of N₂ = (Atomic Mass of N)*2 = (14.00 g/mol)*2 = 28.00 g/mol0.060 mol N₂ * 28.00 g/mol = 1.68 g N₂0.060 only has two significant digits, so the reported answer should have two significant digits as well. Meaning the answer is 1.7 g.
A student is given a sample of an unknown solid and asked to identify it. The student begins by making a list of questions to investigate about the sample.
BRAINLY QUICK!
Which question would be the least useful in helping the student identify the sample?
A) Is the sample soluble in water?
B) What is the weight of the sample?
C) Is the sample attracted to a magnet?
D) What is the melting point of the sample?
Answer:
B) What is the weight of the sample?
Explanation:
The least useful question for the student to identify the sample is "What is the weight of the sample?"
To identify a sample, it is important to know its solubility (homogenous or heterogenous), chemical properties such as melting and boiling point, and whether sample is attracted towards the magnet or not to know the nature of the sample.
Weights is the least useful characteristic of a sample that can help to identify the sample.
Hence, the correct answer is "B) What is the weight of the sample?".
The weight loss of an aluminum alloy corroding in a solution of hydrochloric acid was observed to be 0.250 g/cm2 after an 8 h immersion period [13]. What is the corresponding anodic current density in milliamperes per square centimeter, assuming that all the corrosion is due to the following anodic half-cell reaction:
This question is incomplete, the complete question is;
The weight loss of an aluminum alloy corroding in a solution of hydrochloric acid was observed to be 0.250 g/cm² after an 8 h immersion period [13]. What is the corresponding anodic current density in milliamperes per square centimeter, assuming that all the corrosion is due to the following anodic half-cell reaction:
Al → Al³⁺ + 3e⁻
The atomic weight is 58.7 g/mol
Answer:
Current density in milliamperes per square centimeter is 45.81 mA/cm²
Explanation:
Given the data in the question;
we know that Faradays law of electrolysis states that;
amount of substance produced at each electrode is directly proportional to the quantity of charge flowing through the cell.
so
m = ( Q/F) (M/z)
where m is the mass of substance liberated at an electrode( 0.250 g/cm²)
Q is the total electric charge passed through the substance
F is Faradays constant (96,500 C/mol)
M is the molar mass of the substance( 58.7 g/mol ) and Z is the number of electrons transferred(3)
Also
we know that; Q = It
where I is current and t is time( 8hrs × 60 × 60 = 28800 sec )
we substitute Q = It into our equation'
we have;
m = ( It/F) (M/z)
m = ItM / Fz
mFz = ItM
I = mFz / tM
so we substitute
I = [0.250 g/cm² × 96,500 C/mol × 3] / [ 28800 × 58.7 g/mol]
I = 72375 / 1690560
I = 0.04581 A/cm²
we know that; 1 ampere = 1000 milliampere
so
I = 0.04581 × 1000
I = 45.81 mA/cm²
Therefore, current density in milliamperes per square centimeter is 45.81 mA/cm²
Pls help, science 8th grade question, #11 thx :)
The blood cells that directly attack germs are: *
Answer:
lymphocytes
Explanation:
it consists of the b and the t cells
Shown below is a table with plants and animals with their adaptations.
Using the description of plants and animals in the table above, which biome would all of these organisms would be best adapted to?
Answer:
Desert
Explanation:
The adaptation shown by the given plants and animals shows that they will adapted to the desert biome.
It is so because, due to high temperature of desert some desert animals like camel have the storage of fat in humps or tails; some animals have large ears such as Jackrabbits, it helps to release body heat and adapt in high temperature; plants have thick water holding tissues to reduce water loss in heat and waxy coating that keeps the plants cooler and reduce moisture loss.
Hence, the correct answer is "Desert".
Consider the following data:
HfCo2 = -393.5 kj/mol
HfH20 = -241.82 kj/mol
Hfc2h6 = -84.68 kj/mol
Using these data, calculate Delta HRXN
for this chemical reaction. Round to the nearest whole number.
2C2H6(g) + 7O2(g) -> 4CO2(g) + 6H2O(g)
Answer:
if you ask yahoo answers it will tell you
Explanation:
hope i helped
Answer:
-2856
-792
endothermic, exothermix, exothermic, endothermic
no
Explanation:
PLEASE HELP ASAP I NEED IT HELP PEASEEEEEEEEEEE it’s number 4 (this is science)
Which conclusion was a direct result of the gold foil experiment?
To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. Therefore, each atom in the foil was composed mostly of empty space because most alpha particles directed at the foil.
What is atom?Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.
In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron.
Each atom in the foil was composed mostly of empty space because most alpha particles directed at the foil. This conclusion was the direct result of the gold foil experiment.
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Determine the mass of oxygen that is needed to react with 33 grams of phosphorus.
4P + 5 O2 → 2 P205
A
27.3 grams O2
B
1.33 grams O2
С
213 grams 02
D
42.6 grams 02
Answer:
D = 42.6 g
Explanation:
Given data:
Mass of oxygen needed = ?
Mass of phosphorus react = 33 g
Solution:
Chemical equation:
4P + 5O₂ → 2P₂O₅
Number of moles of phosphorus:
Number of moles = mass/molar mass
Number of moles = 33 g/ 30.97 g/mol
Number of moles = 1.065 mol
now we will compare the moles of P and oxygen.
P : O₂
4 : 5
1.065 : 5/4×1.065 = 1.33mol
Mass of oxygen needed:
Mass = number of moles × molar mass
Mass = 1.33 mol × 32 g/mol
Mass = 42.6 g
1. What is the equality between mL and L?
Answer:
1 liter (L) = 1000 milliliters (mL)
Explanation:
What is the mass of 4.70 mol H2O? Answer in units of g.
Answer:
4.70 moles of water have mass of 84.6g
Explanation:
Given data:
Number of moles of water = 4.70 mol
Mass in gram = ?
Solution:
Formula:
Mass = number of moles × molar mass
Molar mass of water is 18 g/mol
Mass = 4.70 mol × 18 g/mol
Mass = 84.6 g
Thus, 4.70 moles of water have mass of 84.6g.
Based on the organization and colors in the periodic table, which
two elements do you think are most similar in terms of their properties:
magnesium (Mg), barium (Ba), and gold (Au)? Explain.
Answer:
Magnesium (Mg) and Barium (Ba) are most similar in terms of properties.
Explanation:
The periodic table of elements is organized with elements classified by atomic number. Each column in the table represents elements grouped together by protons in the nucleus and as a result of that also charge. The first column of elements have a +1 charge, while the second column have a +2 charge.
Electronegativity, mass and weight can also be determined by the location of elements in the table, with elements becoming more electronegative from left (least amount) to right (most) and more heavy from top to bottom. Because Magnesium and Barium are in the same column, while gold is in a different column (and assigned a different color) it indicates the element gold is not like the other two and has different properties.
Based on the organization of elements in the periodic table, the two elements that will be similar are magnesium (Mg), barium (Ba).
The periodic table is arranged in rows called periods and columns called groups.
Elements in the same group of the periodic table are chemically similar because they have the same number of electrons in their outermost shell and consequently undergo the same kind of chemical reactions.
Having said that, Barium and magnesium both belong to group 2 of the periodic table hence they have the similar properties because they are all members of the same group.
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Which factor can help balance Earth’s temperature?
Answer:
Clouds
Explanation:
Because I just got it right
Please help!!!! Really need to know this!!
The theoretical yield of NaCl : 15 mol
Further explanationGiven
15 mol Na
15 mol Cl₂
Required
The theoretical yield of NaCl
Solution
Reaction
2Na + Cl₂ ⇒ 2NaCl
A theoretical yield is the amount of product that you calculate from the reaction equation according to the product and reactant coefficients
Find limiting reactant (mol : coefficient) :
Na = 15 : 2 = 7.5
Cl₂ = 15 : 1 = 15
The limiting reactant = Na(smaller ratio)
Mol of NaCl based on mol Na as limiting reactant.
From the equation, mol ratio of Na : NaCl = 2 : 2, so mol NaCl = 15 mol
A 558 mg of a mixture of fluorene and benzoic acid was weighed out and subjected to an extraction and recrystallization. After this purification was completed the product crystals were dried and analyzed. The purification procedure produced 185 mg of fluorene and 144 mg of benzoic acid. Calculate the percent composition of this mixture.
Answer:
See explanation
Explanation:
Mass of mixture of fluorene and benzoic acid = 558 mg
Mass of pure fluorene after purification = 185 mg of fluorene
Mass of pure benzoic acid after purification = 144 mg of benzoic acid
Percentage of fluorene int he mixture = 185mg/558mg * 100 = 33.15 %
Percentage of benzoic acid in the mixture = 144mg/558mg * 100 = 25.81 %
Percentage of impurities = 100% - [33.15 + 25.81]
Percentage of impurities = 100 - 58.96
Percentage of impurities = 41.04 %
Do the substances that are reactants in a chemical reaction remain the same after the reaction is complete?