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irakobra [83]
3 years ago
9

Who was the first person to describe a chemical reaction as the recombination of atoms?

Chemistry
1 answer:
Cerrena [4.2K]3 years ago
4 0
Niels Bohr is the first person to describe a chemical reaction as the combination of atoms.
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Given the equation Ca + H2O --> Ca(OH)2 + H2 how many grams of calcium will react completely with 10.0 grams of water? *
Yuki888 [10]

Answer: 11.0 g of calcium will react with 10.0 grams of water.

Explanation:

To calculate the moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}

moles of H_2O

\text{Number of moles}=\frac{10.0g}{18g/mol}=0.55moles

The balanced chemical equation is:

Ca+2H_2O\rightarrow Ca(OH)_2+H_2

According to stoichiometry :

2 moles of H_2O require = 1 mole of Ca

Thus 0.55 moles of H_2O require=\frac{1}{2}\times 0.55=0.275moles  of Ca  

Mass of Ca=moles\times {\text {Molar mass}}=0.275moles\times 40g/mol=11g

Thus 11.0 g of calcium will react with 10.0 grams of water.

3 0
3 years ago
How might the biodiversity of a mowed lawn compare to that of huge weedy field?
Dennis_Churaev [7]

Answer: The mowed lawn is the one from where the grasses are removed by using the machines or tools.

Explanation:

The mowed lawn is expected to have low number of species as the grasses may be few or scanty thus can support the population of few species like insects, mice, birds, and small number of grazing animals. On the other hand the weedy field can be hub of insects, reptiles like snakes, small mammals, and large mammals. Large weed field can provide food, and habitat to the large number of species. This will support the increase in biodiversity as compared to the mowed lawn.

5 0
2 years ago
A bond where electrons are transferred from a cation to an anion is called a (n) ___________bond.\
emmasim [6.3K]
When elements transfer electrons from a cation and an anion it called ionic bond.
6 0
3 years ago
What is the molecular structure of water? What are the physical and chemical properties of water?
Slav-nsk [51]
Water (H
2O) is a polar inorganic compound that is at room temperature a tasteless and odorless liquid, which is nearly colorless apart from an inherent hint of blue. It is by far the most studied chemical compound and is described as the "universal solvent" [18][19] and the "solvent of life".[20] It is the most abundant substance on Earth[21] and the only common substance to exist as a solid, liquid, and gas on Earth's surface.[22] It is also the third most abundant molecule in the universe.[21]

Water (H
2O)





NamesIUPAC name

water, oxidane

Other names

Hydrogen hydroxide (HH or HOH), hydrogen oxide, dihydrogen monoxide (DHMO) (systematic name[1]), hydrogen monoxide, dihydrogen oxide, hydric acid, hydrohydroxic acid, hydroxic acid, hydrol,[2] μ-oxido dihydrogen

Identifiers

CAS Number

7732-18-5 

3D model (JSmol)

Interactive image

Beilstein Reference

3587155ChEBI

CHEBI:15377 

ChEMBL

ChEMBL1098659 

ChemSpider

937 

Gmelin Reference

117

PubChem CID

962

RTECS numberZC0110000UNII

059QF0KO0R 

InChI

InChI=1S/H2O/h1H2 

Key: XLYOFNOQVPJJNP-UHFFFAOYSA-N 

SMILES

O

Properties

Chemical formula

H
2OMolar mass18.01528(33) g/molAppearanceWhite crystalline solid, almost colorless liquid with a hint of blue, colorless gas[3]OdorNoneDensityLiquid:[4]
0.9998396 g/mL at 0 °C
0.9970474 g/mL at 25 °C
0.961893 g/mL at 95 °C
Solid:[5]
0.9167 g/ml at 0 °CMelting point0.00 °C (32.00 °F; 273.15 K) [a]Boiling point99.98 °C (211.96 °F; 373.13 K) [6][a]SolubilityPoorly soluble in haloalkanes, aliphaticand aromatic hydrocarbons, ethers.[7]Improved solubility in carboxylates, alcohols, ketones, amines. Miscible with methanol, ethanol, propanol, isopropanol, acetone, glycerol, 1,4-dioxane, tetrahydrofuran, sulfolane, acetaldehyde, dimethylformamide, dimethoxyethane, dimethyl sulfoxide, acetonitrile. Partially miscible with Diethyl ether, Methyl Ethyl Ketone, Dichloromethane, Ethyl Acetate, Bromine.Vapor pressure3.1690 kilopascals or 0.031276 atm[8]Acidity (pKa)13.995[9][10][b]Basicity (pKb)13.995Conjugate acidHydroniumConjugate baseHydroxideThermal conductivity0.6065 W/(m·K)[13]

Refractive index (nD)

1.3330 (20 °C)[14]Viscosity0.890 cP[15]Structure

Crystal structure

Hexagonal

Point group

C2v

Molecular shape

Bent

Dipole moment

1.8546 D[16]Thermochemistry

Heat capacity (C)

75.375 ± 0.05 J/(mol·K)[17]

Std molar
entropy (So298)

69.95 ± 0.03 J/(mol·K)[17]

Std enthalpy of
formation (ΔfHo298)

−285.83 ± 0.04 kJ/mol[7][17]

Gibbs free energy (ΔfG˚)

−237.24 kJ/mol[7]
6 0
3 years ago
A ___ such as h20 is a symbol that shows the elements in a compound and the ratio of atoms
KATRIN_1 [288]
I think the answer is 15
4 0
3 years ago
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