Determine whether each melting point observation corresponds to a pure sample of a single compound or to an impure sample with multiple compounds.

a. Wide melting point range __________
b. Experimental melting point is close to literature value _________
c. Experimental melting point is below literature value _________
d. Narrow melting point range __________

Answer:

At is a metalloid

Explanation:  Meaning that it displays some of the characteristics of a metal but can also display characteristics of nonmetals.  Silicon is one such element.  Elemental Silicon has a dark lustrous metallic appearance but it is quite brittle.  Some authorities include Astatine as a halogen as it has seven electrons in its valence shell placing it just below iodine in period 17 VIIA.  Additionally, because Astatine is only ever found naturally as the result of radioactive decay from more dense elements it is the rarest naturally occurring element in Earth's crust.

I hope this helps at least a little.

Regards,

JR Holt

Chemist retired  

Answer:

0.043 grams

Explanation:

We can find the mass of carbon dioxide as follows:

[tex] m = n*M [/tex]

Where:

n: is the number of moles

M: is the molar mass = 44.01 g/mol

First, we need to calculate the number of moles. We can use the Ideal gas equation:

[tex] PV = nRT [/tex]

Where:

P: is the pressure = 0.945 atm

V: is the volume = 25.0 mL  

R: is the gas constant = 0.082 L*atm/(K*mol)

T: is the tempearture = 22.5 °C

[tex]n = \frac{PV}{RT} = \frac{0.945 atm*25 mL*\frac{1 L}{1000 mL}}{0.082 L*atm/K*mol*(22.5 + 273) K} = 9.75 \cdot 10^{-4} moles[/tex]

Hence, the mass is:

[tex]m = 9.75 \cdot 10^{-4} moles*44.01 g/mol = 0.043 g[/tex]

Therefore, 0.043 grams were collected.

I hope it helps you!

Answer:

2.42x10⁹ years is the age of the rock

Explanation:

The decay of an isotope follows the equation:

Ln[A] = -kt + Ln[A]₀

Where [A] is amount of isotope after time t, k is decay constant and [A]₀ is the initial amount of the isotope

To find decay constant from half-life:

k = ln2 / half-life

k = ln2 / 1.26x10⁹years

k = 5.501x10⁻¹⁰ years⁻¹

As in the reaction, K-40 produce Ar-40:

[A] = 0.359mmol

[A]₀ = 0.359mmol + 1.000mmol = 1.359mmol

Replacing:

Ln[0.359mmol] = -5.501x10⁻¹⁰ years⁻¹t + Ln[1.359mmol]

-1.3312 = -5.501x10⁻¹⁰ years⁻¹t

t = 2.42x10⁹ years is the age of the rock

Answer:

The answer is below

Explanation:

Yes, there are multiple combinations.

Firstly, a solvent or soap combination could be used as a polar solvent with soap. In this way, the nonpolar region of the soap molecules would mix directly with the stain while the solvent would surround the soap-stain micelle.

Secondly, another method or way is to have a combination of a nonpolar solvent with no soap. In this method, however, it is the solvent that would mix directly with the stain.

Answer:

On the periodic table,periods are horizontal rows (across) the periodic table while groups are vertical columns (down) the table.We have groups in the periodic table like transition metals,rare earth,alkali metals ,alkaline earth metals halogens and noble gases

Answer:

Horizontal row call period and vertical column called group!

Physical,chemical, reaction procedure, shape,size, enthalpy of dissociation, bonding,non bonding, various things that segregated group and period....

Answer:

1.62 g

Explanation:

Given that:

Concentration of HCN = 0.119 M

Assuming the ka 4.00 × 10⁻¹⁰

The pKa of  HCN (hydrocyanic acid)  = -log (Ka)

= - log ( 4.00 × 10⁻¹⁰)

= 9.398

pH of buffer = 8.809

Using Henderson Hasselbach equation:

[tex]pH = pKa + log \dfrac{[conjugate\ base ]}{acid}[/tex]

[tex]pH = pKa + log \dfrac{[CN^-]}{[HCN]}[/tex]

[tex]8.809 = 9.398 +log \dfrac{[CN^-]}{[HCN]}[/tex]

[tex]log \dfrac{[CN^-]}{[HCN]}= 8.809 - 9.398[/tex]

[tex]log \dfrac{[CN^-]}{[HCN]}= -0.589[/tex]

[tex]\dfrac{[CN^-]}{[HCN]}= 0.2576[/tex]

[CN^-] = 0.2576[HCN]

[CN^-] = 0.2756 (0.119) L

[CN^-] = 0.033 M

∴

The amount of NaCN (sodium cyanide) is calculated as follows:

[tex]= 1.00 L \times \dfrac{0.033 \ mol \ NacN }{1 \ L } \times \dfrac{49.01 \ g}{1 \ mol \ of \ NacN}[/tex]

= 1.62 g

Answer:

hjfhgjgjgjghgjgjhgjhhjh

Answer:

Its D Are in random motion

i hope it will help you if not soo sorry :)

Answer:

33.8 g Solution

Explanation:

A chemistry student needs 15.0 g of methanol for an experiment. The concentration of ethanol in the solution is 44.4% w/w, that is, there are 44.4 g of methanol every 100 g of solution. The mass of solution that would contain 15.0 g of methanol is:

15.0 g Methanol × 100 g Solution/44.4 g Methanol = 33.8 g Solution

Since 33.8 g are required and 320. g are available, there is enough solution for the requirements.

Answer:

1. CrCl₃     2. MnO₂     3. MgCO₃

Explanation:

For a compound to be neutral, we need the same number of positive charges and negative charges.

1. Cr³⁺ ions and Cl⁻ ions. We will need 1 Cr³⁺ cation and 3 Cl⁻ anions. The chemical formula is CrCl₃.

2. Mn⁴⁺ ions and O²⁻ ions. We will need 1 Mn⁴⁺ cation and 2 O²⁻ anions. The chemical formula is MnO₂.

3. Mg²⁺ ions and CO₃²⁻ ions. We will need 1 Mg²⁺ cation and 1 CO₃²⁻ anion The chemical formula is MgCO₃.

Answer:

0.10 M Ca(CH3COO)2- Less soluble than in pure water.

0.10 M K2SO3- Less soluble than in pure water.

0.10 M NaNO3 - More soluble than in pure water.

0.10 M KCH3COO- Similar solubility as in pure water.

Explanation:

We have to cast our minds back to the idea of common ions effect. If any ion is already present in solution, the presence of that ion in solution prevents any solute containing a common ion with the solution from dissolving in that solution. In order words, the presence of a common ion makes a solute less soluble in a solvent than it is in pure water.

For instance, 0.10 M Ca(CH3COO)2 and K2SO3 both contain Ca^2+ and SO3^2- ions respectively which are also contained in the solute calcium sulfite.

The presence of these common ions in solution makes calcium sulfite less soluble in these solutions than it is in pure water because the equilibrium position for the dissolution of the solute lies towards the left hand side.

However, calcium sulfite is more soluble in 0.10 M NaNO3 than in pure water due to displacement reaction between the ions in solution.

The solubility of calcium sulfite and 0.10 M KCH3COO in pure water is quite comparable.

Answer:

false

Explanation:

False, water is a polyatomic molecule made up of two atoms of oxygen and 1 atom of hydrogen.

Explanation:

So, from this, we can conclude that water is a polyatomic molecule made up of two atoms of oxygen and 1 atom of hydrogen.

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Answer:

C. 12 × 16

Explanation:

Let mH be the mass of atoms of hydrogen and mO be the mass of atoms of oxygen.  The atoms of oxygen have 16 times the mass of atoms of hydrogen. That is,

mO = 16 mH   [1]

Let mX be the mass of the atoms of X. Atoms of element X have 12 times the mass of atoms of oxygen. That is,

mX = 12 mO   [2]

If we substitute [1] in [2], we get

mX = 12 × 16 mH

If mH is 1, we get,

mX = 12 × 16 × 1

mX = 12 × 16

Answer:

d

Explanation:

cuaase that it sirhal

The chemical formula PbCl₂(s) represented by:

A) a substance

The chemical formula PbCl₂(s) represents a substance. A substance is a single, pure chemical entity with a definite composition. It can be an element, a compound, or an alloy.

A solution is a homogeneous mixture of two or more substances. A homogeneous mixture is a mixture in which the components are evenly distributed throughout the mixture.

A heterogeneous mixture is a mixture in which the components are not evenly distributed throughout the mixture.

A reaction is a process in which one or more substances are transformed into one or more new substances.

Therefore, the chemical formula PbCl₂(s) represents a substance, and the answer is (A).

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Answer:

.04 cg/L

Explanation:

Answer:

A new fictitious element was discovered.

It is a metal named jolmium, J, and it has three valence electrons.

If it combines with iodine it forms jolmium iodide. Answer the following questions.

a.Is this compound ionic or covalent

b. What is the formula of Jolmium iodide?

c. What is the charge on the metal J in this compound?

d. Explain how you know that is the charge?

Explanation:

It is given the element jolmium J is a metal with three valence electrons.

Since metals are highly electropositive, they lose electrons easily and form cations (Ions with a positive charge).

[tex]J^{3+}[/tex] ion will be formed.

b) The formula of jolmium iodide is shown below:

[tex]J^{+3} I^{-1}\\The formula becomes:\\JI_{3}[/tex]

a) The compound is ionic in nature.

Since the compound formed between a metal atom and a nonmetal atom will take place by transfer of electrons.

Hence, it is ionic in nature.

c) The charge on the metal J in this compound is +3.

d) Given J has three valence electrons.

That means it can lose three electrons to form a bond.

So, its valency is three.

Answer:

1.9 × 10² g NaN₃

1.5 g/L

Explanation:

Step 1: Write the balanced decomposition equation

2 NaN₃(s) ⇒ 2 Na(s) + 3 N₂(g)

Step 2: Calculate the moles of N₂ formed

N₂ occupies a 80.0 L bag at 1.3 atm and 27 °C (300 K). We will calculate the moles of N₂ using the ideal gas equation.

P × V = n × R × T

n = P × V / R × T

n = 1.3 atm × 80.0 L / (0.0821 atm.L/mol.K) × 300 K = 4.2 mol

We can also calculate the mass of nitrogen using the molar mass (M) 28.01 g/mol.

4.2 mol × 28.01 g/mol = 1.2 × 10² g

Step 3: Calculate the mass of NaN₃ needed to form 1.2 × 10² g of N₂

The mass ratio of NaN₃ to N₂ is 130.02:84.03.

1.2 × 10² g N₂ × 130.02 g NaN₃/84.03 g N₂ = 1.9 × 10² g NaN₃

Step 4: Calculate the density of N₂

We will use the following expression.

ρ = P × M / R × T

ρ = 1.3 atm × 28.01 g/mol / (0.0821 atm.L/mol.K) × 300 K = 1.5 g/L

Answer:

V₂ = 1500 Liters ( 2 sig. figs.)

Explanation:

Given the following gas law variables:

P₁ = 110.0KPa           P₂ = 25KPa

V₁ = 410 Liters          V₂ = ?

T₁ = 17°C ( = 290K)   T₂ = -27°C  ( = 248K)

P₁V₁/₁T₁ = P₂V₂/T₂  =>  V₂ = V₁(P₁/P₂)(T₂/T₂)

V₂ = 410L(110.0KPa/25KPa)(248k/290K) = 1542 L (calc. ans.)

V₂ = 1500 Liters ( 2 sig. figs.)

Molecule is the general term used to describe any atoms that are connected by chemical bonds. Every combination of atoms is a molecule. A compound is a molecule made of atoms from different elements. All compounds are molecules, but not all molecules are compounds.

One example of a molecule is [tex]Cl_2[/tex] (chlorine).

Examples of a compound is NaCl (sodium chloride) or [tex]H_2O\\[/tex] (water)

Answer:

C. [tex]H_2S\rightarrow S+2H^++2e^-[/tex]

Explanation:

Hello there!

In this case, according to the given chemical reaction, it turns out possible to realize there is one sulfur atom on each side of the chemical equation but two hydrogen atoms on the left and one on the right, which means the latter must be balanced in agreement to the law of conservation of mass.

In such a way, by setting a 2 on H⁺, the reaction will be balanced:

[tex]H_2S\rightarrow S+2H^+[/tex]

Now, we count the transfer electrons for sulfur from -2 to 0 as 2e⁻ on the right, which will match with the option C.

[tex]H_2S\rightarrow S+2H^++2e^-[/tex]

Regards!

Answer:

See Explanation

Explanation:

Rate of reaction refers to how quickly or slowly a reaction proceeds. The rate of reaction depends on certain factors.

Two among the factors that affect the rate of reaction are the concentration of reactants and the surface area of reactants.

The more the concentration of reactants, the faster the rate of reactants because there is a high possibility of collision between reactants. Also, the higher the surface area of reactants, the greater the rate of reaction.

In flour mills and coal mines where there is a large amount (concentration) of combustible materials and the particles are powdered (high surface area), there is a greater risk of explosion due to a high rate of reaction owing to a combination of the two factors discussed above.

Answer:

Hence,  

1) removed  

2) drained through the stopcock  

3) get eye level with  

4) slow the draining  

5) switch to a new flask

Explanation:

After mixing the solutions in a separatory funnel, the stopper should be removed and the liquid should be drained through the stopcock, and the layers allowed to separate. When you get close to the interface between the layers, get eye level with the funnel and turn over to slow the draining heat up until the first layer is collected. Switch to a new flask get eye level with it to collect the second layer.

Answer:

Option D. 4

Explanation:

The oxidation number of nitrogen (N) in NO₂ can be obtained as follow:

Oxidation number of O = –2

Oxidation number of N =?

N + 2O = 0

N + 2(–2) = 0

N – 4 = 0

Collect like terms

N = 0 + 4

N = +4

Thus, the oxidation number of nitrogen (N) in NO₂ is +4

Answer:

Ka = [H⁺] × [CN⁻] / [HCN]

Explanation:

Cyanhydric acid is a weak acid, according to the following equation:

HCN(aq) ⇄ H⁺(aq) + CN⁻(aq)

The acid ionization constant (Ka) is equal to the product of the concentrations of the ions raised to the stoichiometric coefficients divided by the concentration of the undissociated acid raised to its stoichiometric coefficient.

Ka for HCN is:

Ka = [H⁺] × [CN⁻] / [HCN]

Answer:

Correct answer:

The equilibrium expression is defined as the ratio of the concentration of products divided by the concentration of the reactants. Each reactant or product is raised to the power corresponding to its coefficient in the balanced chemical equation.

Explanation:

Explanation:

Answer

Open in answr app

Correct option is

C

148

1 atom of Mg=1x24=24

2 atom of N=2x14=28

6 atom of O=6x16=96

Total mass=148

Answer:

The correct answer is - The net force is zero.

Explanation:

When an object moves on the surface with the same or constant acceleration which means there is no gain or loss of the speed it shows that all the forces of the object are at a point of zero.

If there would be any force applied on the object there must be some change in the velocity or acceleration but in this case there is no loss or gain of speed which means there is the object's net force is zero.

Therefore, option B is correct.

Answer:

Titanium - Metal

Gold - Metal

Argon - noble gas

Thallium - Metal

Explanation:

A metal is a species that easily looses electrons to yield a positive ion. Metals are found in the left hand side of the periodic table.

Thallium is a groups 13 metal, gold is a group 11 metal while titanium is a 4 metal.

However, argon is a noble gas hence it belongs to groups 18 of the periodic table.

Titanium -metal

gold - metal,

Argon - noble gas

Thallium -metal, transition metal

Explanation:

In modern periodic table :

So, from this, we can match the given elements as:

Titanium -metal

gold - metal,

Argon - noble gas

Thallium -metal. transition metal

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