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3 years ago

What are the characteristics that make elements different from compounds?

2 answers:

6 0

Elements are the simplest form of a pure substance and cannot be broken down by any means, while compounds are chemically combined elements that can be broken down by chemical means

777dan777 [17]3 years ago

3 0

Compounds are many elements chemically combined and can be broken down, element is the opposite

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g Write a molecular equation for the precipitation reaction that occurs (if any) when the following solutions are mixed. If no r

Mrac [35]

Answer:

CuBr₂(aq) + Pb(CH₃COO)₂(aq) → Cu(CH₃COO)₂(aq) + PbBr₂ (s)↓

Explanation:

We identify the reactants:

CuBr₂ and Pb(CH₃COO)₂

The products will be: Cu(CH₃COO)₂ and PbBr₂

You may know these information:

Salts from acetate are soluble.

Bromide can make solid salts with these cations: Ag⁺, Pb²⁺, Hg₂²⁺, Cu⁺

PbBr₂ is formed, so this will be our precipitate

The equation is:

CuBr₂(aq) + Pb(CH₃COO)₂(aq) → Cu(CH₃COO)₂(aq) + PbBr₂ (s)↓

8 0

3 years ago

The chart below lists data on four different projects designed to restore a wetlands habitat destroyed by human activity and a r

snow_lady [41]

Answer:

Project 3.

Explanation:

Project 3's anticipated cost is 12 to 17 million dollars. It is a lower anticipated cost than Project 2 and Project 4, but higher than Project 1 by one million dollars at maximum cost anticipation. Additionally, the percentage of wildlife to benefit is 70-80%, which is second to the most wildlife to benefit which is Project 4 at 75-80%.

And finally, for community support for Project 3 - the chart lists it as high. This outclasses Project 2 and Project 4, but balances with Project 1. However, Project 1 costs 13 to 16 million dollars and only benefits 15-25% of wildlife.

5 0

3 years ago

From the value Kf=1.2×109 for Ni(NH3)62+, calculate the concentration of NH3 required to just dissolve 0.016 mol of NiC2O4 (Ksp

Nina [5.8K]

Answer: The concentration of $NH_3$ required will be 0.285 M.

Explanation:

To calculate the molarity of $NiC_2O_4$ , we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$

Moles of $NiC_2O_4$ = 0.016 moles

Volume of solution = 1 L

Putting values in above equation, we get:

$\text{Molarity of }NiC_2O_4=\frac{0.016mol}{1L}=0.016M$

For the given chemical equations:

$NiC_2O_4(s)\rightleftharpoons Ni^{2+}(aq.)+C_2O_4^{2-}(aq.);K_{sp}=4.0\times 10^{-10}$

$Ni^{2+}(aq.)+6NH_3(aq.)\rightleftharpoons [Ni(NH_3)_6]^{2+}+C_2O_4^{2-}(aq.);K_f=1.2\times 10^9$

Net equation: $NiC_2O_4(s)+6NH_3(aq.)\rightleftharpoons [Ni(NH_3)_6]^{2+}+C_2O_4^{2-}(aq.);K=?$

To calculate the equilibrium constant, K for above equation, we get:

$K=K_{sp}\times K_f\\K=(4.0\times 10^{-10})\times (1.2\times 10^9)=0.48$

The expression for equilibrium constant of above equation is:

$K=\frac{[C_2O_4^{2-}][[Ni(NH_3)_6]^{2+}]}{[NiC_2O_4][NH_3]^6}$

As, $NiC_2O_4$ is a solid, so its activity is taken as 1 and so for $C_2O_4^{2-}$

We are given:

$[[Ni(NH_3)_6]^{2+}]=0.016M$

Putting values in above equations, we get:

$0.48=\frac{0.016}{[NH_3]^6}}$

$[NH_3]=0.285M$

Hence, the concentration of $NH_3$ required will be 0.285 M.

7 0

3 years ago

A student explained to the class that helium has 8 valence electrons because it is in group 18. Is the student correct?

lys-0071 [83]

The student is incorrect because helium has 2 valence electrons and it's in group 18 because the first energy level is full. Although helium is placed in Group 18 which generally has 8 valence electrons, it does not have 8 valence electrons as the student suggested. It was grouped together with the noble gases because it exhibits similar properties with them.

5 0

4 years ago

Indicate which of the following statements is FALSE.a. Covalent bonds connect nucleotides in a strand; noncovalent interactions

LenaWriter [7]

Answer:

The false statement is d Avery,Macleod and McCarty showed that DNA is the genetic information of cells and RNA is the genetic information in the viruses .

Explanation:

Avery,Macleod and MacCarty showed that DNA is the genetic material of the cell.

On the other hand Fraenkel, Conrat and Sanger carried out their experiment on tobacco mosaic virus to prove that RNA act as genetic material in some viruses.

8 0

4 years ago