Friday

February 24, 2017
Total # Posts: 15

**Math**

A ball is thrown upwards from ground level and reaches a height of "h" metres after "t" seconds, given by the formula h=20t - 5t^2

*October 5, 2016*

**trig**

cotx = -2 and 0 less than or equal to x less than or equal to pi Find sin2x and cos2x How to get the answers of sin2x = -4/5, cos2x = 3/5?

*May 1, 2008*

**trig**

sinx = 4/5 and x terminates in Quadrant II Find sin2x and cos2x How to get the answers, which are sin2x = -24/25, cos2x = -7/25?

*May 1, 2008*

**trig**

tanx = 5/12 and sinx<0 Find sin2x and cos2x How to get the answers of sin2x = 120/169 and cos 2x = 119/169?

*May 1, 2008*

**chemistry**

Chromium metal can be plated onto an object from an acidic solution of dichrmonate tions. What average current is required to plate 17.8 g of chronium metal in a time of 2.20 h? ( you will need to construct your own equation for the half-reaction)

*April 23, 2008*

**chemistry**

Will this help? A car bumper is plated with chronium using chronium(III)ions in solution. If a current of 54 A flows into a cell for 45 minutes 30 s, determine the mass of chronium deposited.

*April 22, 2008*

**chemistry**

What am I doing wrong? If a current of 54 A flows into a cell for 45 minutes 30 s, determine the mass of chronium deposited. My answer: 54 x 2730 s = 147420 147430/96485 = 1.52 mols m = n x M =1.52 x 52 = 79.5

*April 22, 2008*

**chemistry**

Balance the follwoing chemical reaction in an acidic solution __H2O(l) + __H^+(aq)+ OH^-(aq)+ __ CR2O7^2-(aq) + __ Cl^-(aq)---> __ Cr^3-+ __Cl2(aq)+ __H2O(l) + __H^+(aq) + __ OH^-(aq)

*April 22, 2008*

**chemistry**

What am I doing wrong? If a current of 54 A flows into a cell for 45 minutes 30 s, determine the mass of chronium deposited. My answer: 54 x 2730 s = 147420 147430/96485 = 1.52 mols m = n x M =1.52 x 52 = 79.5

*April 22, 2008*

**trig**

What is the shift along x of the following trig functions? y = (3sinx/2) + 4 y = -2sin(x)-4 y = sin(-3x + 3)

*April 21, 2008*

**chemistry**

Enter the oxidation number with the sign above each element H2 OH^- Mg^2+ CO3^2-

*April 20, 2008*

**chemistry**

What is the pH of a 1.24 mol/L solution of HCN(aq) if its Ka = 6.2 x 10-10? Rate my answer please For your understanding: HCN ⇌ H+ + CN-, Ka = 6.2x10^-10 = [H+]*[CN-]/[HCN] Notice the H+ and CN- ions are generated in pairs during HCN dissociation, hence [H+] = [CN-]. ...

*April 20, 2008*

**trig**

I am doing a similar assignment as Anaa please help! y = 3cos(x-1) Amplitude: Period: Two x - intercepts: y-intercept: Domain: Range: Shift along x: Shift along y: Kind of reflection Thank you so much!

*April 19, 2008*

**chemistry**

What is the percent ionization of a 1.38 mol/L weak acid if its Ka = 2.7 x 10^-6? Thanks again!

*April 19, 2008*

**chemistry**

Find the temperature at which the reaction below is spontaneous given this data: Hf^o of NH3(g) = - 46 kJ/mol, S^o of NH3(g) = 192.5 J/mol·K, S^o of N2(g) = 191.5 J/mol·K, S^o of H2(g) = 130.6 J/mol·K. N2(g) + 3H2(g) <-----> 2NH3(g)

*April 19, 2008*

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