A piercing break from Rimma Petlevannaya released Lucy Millard to race down the right wing for the home side's first try shortly before half-time. The full-back added a further five points after the break, showing deftness of foot to weave through the Welsh defence. Chalmers converted to give them a 15-0 lead.
Wales looked to claw back into contention in the 64th minute with a try from centre Lowri Jones. Scrum-half Kerry Jenkins' chip over the line appeared lost as the Scottish defence looked set to clear, but a fumble of the ball allowed Jones to capitalise and touch down for Wales' only points.
Any hope of the visitors winning through were dashed in the dying minutes when Suzi Newton slipped through the Welsh back-line for a final try.
Elen Evans; Non Evans; Rhian Williams; Lowri Jones; Louise Rickard (Hayley Baxter); Awen Thomas; Kerry Jenkins; Louise Horgan; Jenny Davies (Sophie Williams); Claire Horgan; Ayla Rose (Rachel Brown); Claire
Donovan (Becky Dando); Catrina Nicholas; Kylie Wilson; Emma Phillips